diff --git a/cli/node/src/backend/platform.ts b/cli/node/src/backend/platform.ts
index 49906b8bd..0819bf3cb 100644
--- a/cli/node/src/backend/platform.ts
+++ b/cli/node/src/backend/platform.ts
@@ -17,6 +17,10 @@ import {
 	type SearchOptions,
 } from "./base.js";
 
+function encodePathSegment(value: unknown): string {
+	return encodeURIComponent(String(value));
+}
+
 export class PlatformBackend implements Backend {
 	private baseUrl: string;
 	private headers: Record<string, string>;
@@ -218,9 +222,13 @@ export class PlatformBackend implements Backend {
 	}
 
 	async get(memoryId: string): Promise<Record<string, unknown>> {
-		return (await this._request("GET", `/v1/memories/${memoryId}/`, {
-			params: { source: "CLI" },
-		})) as Record<string, unknown>;
+		return (await this._request(
+			"GET",
+			`/v1/memories/${encodePathSegment(memoryId)}/`,
+			{
+				params: { source: "CLI" },
+			},
+		)) as Record<string, unknown>;
 	}
 
 	async listMemories(
@@ -277,9 +285,13 @@ export class PlatformBackend implements Backend {
 		if (content) payload.text = content;
 		if (metadata) payload.metadata = metadata;
 		payload.source = "CLI";
-		return (await this._request("PUT", `/v1/memories/${memoryId}/`, {
-			json: payload,
-		})) as Record<string, unknown>;
+		return (await this._request(
+			"PUT",
+			`/v1/memories/${encodePathSegment(memoryId)}/`,
+			{
+				json: payload,
+			},
+		)) as Record<string, unknown>;
 	}
 
 	async delete(
@@ -297,9 +309,13 @@ export class PlatformBackend implements Backend {
 			})) as Record<string, unknown>;
 		}
 		if (memoryId) {
-			return (await this._request("DELETE", `/v1/memories/${memoryId}/`, {
-				params: { source: "CLI" },
-			})) as Record<string, unknown>;
+			return (await this._request(
+				"DELETE",
+				`/v1/memories/${encodePathSegment(memoryId)}/`,
+				{
+					params: { source: "CLI" },
+				},
+			)) as Record<string, unknown>;
 		}
 		throw new Error("Either memoryId or --all is required");
 	}
@@ -323,7 +339,7 @@ export class PlatformBackend implements Backend {
 		for (const [entityType, entityId] of entities) {
 			results[entityType] = (await this._request(
 				"DELETE",
-				`/v2/entities/${entityType}/${entityId}/`,
+				`/v2/entities/${encodePathSegment(entityType)}/${encodePathSegment(entityId)}/`,
 				{ params: { source: "CLI" } },
 			)) as Record<string, unknown>;
 		}
@@ -386,9 +402,9 @@ export class PlatformBackend implements Backend {
 	}
 
 	async getEvent(eventId: string): Promise<Record<string, unknown>> {
-		return (await this._request("GET", `/v1/event/${eventId}/`)) as Record<
-			string,
-			unknown
-		>;
+		return (await this._request(
+			"GET",
+			`/v1/event/${encodePathSegment(eventId)}/`,
+		)) as Record<string, unknown>;
 	}
 }
diff --git a/cli/node/tests/platform-backend.test.ts b/cli/node/tests/platform-backend.test.ts
index 1857f52bf..cb577a638 100644
--- a/cli/node/tests/platform-backend.test.ts
+++ b/cli/node/tests/platform-backend.test.ts
@@ -2,7 +2,7 @@
  * Tests for the Platform backend (mem0 Platform API client).
  */
 
-import { describe, it, expect, vi } from "vitest";
+import { beforeEach, describe, expect, it, vi } from "vitest";
 import { PlatformBackend } from "../src/backend/platform.js";
 import { createDefaultConfig } from "../src/config.js";
 
@@ -12,6 +12,22 @@ function makeBackend(): PlatformBackend {
   return new PlatformBackend(createDefaultConfig().platform);
 }
 
+function mockFetch() {
+  const fetchMock = vi.fn().mockResolvedValue({
+    ok: true,
+    status: 200,
+    headers: { get: vi.fn().mockReturnValue(null) },
+    json: vi.fn().mockResolvedValue({ message: "ok" }),
+  });
+  vi.stubGlobal("fetch", fetchMock);
+  return fetchMock;
+}
+
+beforeEach(() => {
+  vi.restoreAllMocks();
+  vi.unstubAllGlobals();
+});
+
 describe("deleteEntities", () => {
   it("returns all results keyed by entity type for a multi-entity delete", async () => {
     const backend = makeBackend();
@@ -50,3 +66,35 @@ describe("deleteEntities", () => {
     );
   });
 });
+
+describe("PlatformBackend path encoding", () => {
+  it("encodes memory IDs before interpolating them into paths", async () => {
+    const fetchMock = mockFetch();
+    const backend = makeBackend();
+
+    await backend.get("mem/a?b#c");
+    await backend.update("mem/a?b#c", "updated");
+    await backend.delete("mem/a?b#c");
+
+    const urls = fetchMock.mock.calls.map((call) => call[0]);
+    expect(urls).toEqual([
+      "https://api.mem0.ai/v1/memories/mem%2Fa%3Fb%23c/?source=CLI",
+      "https://api.mem0.ai/v1/memories/mem%2Fa%3Fb%23c/",
+      "https://api.mem0.ai/v1/memories/mem%2Fa%3Fb%23c/?source=CLI",
+    ]);
+  });
+
+  it("encodes entity and event IDs before interpolating them into paths", async () => {
+    const fetchMock = mockFetch();
+    const backend = makeBackend();
+
+    await backend.deleteEntities({ userId: "org/team?active#frag" });
+    await backend.getEvent("evt/a?b#c");
+
+    const urls = fetchMock.mock.calls.map((call) => call[0]);
+    expect(urls).toEqual([
+      "https://api.mem0.ai/v2/entities/user/org%2Fteam%3Factive%23frag/?source=CLI",
+      "https://api.mem0.ai/v1/event/evt%2Fa%3Fb%23c/",
+    ]);
+  });
+});
diff --git a/cli/python/src/mem0_cli/backend/platform.py b/cli/python/src/mem0_cli/backend/platform.py
index a0e5badd9..1df3deadd 100644
--- a/cli/python/src/mem0_cli/backend/platform.py
+++ b/cli/python/src/mem0_cli/backend/platform.py
@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 from typing import Any
+from urllib.parse import quote
 
 import httpx
 
@@ -11,6 +12,10 @@ from mem0_cli.backend.base import Backend
 from mem0_cli.config import PlatformConfig
 
 
+def _encode_path_segment(value: Any) -> str:
+    return quote(str(value), safe="")
+
+
 class PlatformBackend(Backend):
     """Backend that talks to the mem0 Platform API."""
 
@@ -196,7 +201,11 @@ class PlatformBackend(Backend):
         )
 
     def get(self, memory_id: str) -> dict:
-        return self._request("GET", f"/v1/memories/{memory_id}/", params={"source": "CLI"})
+        return self._request(
+            "GET",
+            f"/v1/memories/{_encode_path_segment(memory_id)}/",
+            params={"source": "CLI"},
+        )
 
     def list_memories(
         self,
@@ -250,7 +259,11 @@ class PlatformBackend(Backend):
         if metadata:
             payload["metadata"] = metadata
         payload["source"] = "CLI"
-        return self._request("PUT", f"/v1/memories/{memory_id}/", json=payload)
+        return self._request(
+            "PUT",
+            f"/v1/memories/{_encode_path_segment(memory_id)}/",
+            json=payload,
+        )
 
     def delete(
         self,
@@ -274,7 +287,11 @@ class PlatformBackend(Backend):
                 params["run_id"] = run_id
             return self._request("DELETE", "/v1/memories/", params=params)
         elif memory_id:
-            return self._request("DELETE", f"/v1/memories/{memory_id}/", params={"source": "CLI"})
+            return self._request(
+                "DELETE",
+                f"/v1/memories/{_encode_path_segment(memory_id)}/",
+                params={"source": "CLI"},
+            )
         else:
             raise ValueError("Either memory_id or --all is required")
 
@@ -302,7 +319,9 @@ class PlatformBackend(Backend):
         results: dict = {}
         for entity_type, entity_id in entities.items():
             results[entity_type] = self._request(
-                "DELETE", f"/v2/entities/{entity_type}/{entity_id}/", params={"source": "CLI"}
+                "DELETE",
+                f"/v2/entities/{_encode_path_segment(entity_type)}/{_encode_path_segment(entity_id)}/",
+                params={"source": "CLI"},
             )
         return results
 
@@ -348,7 +367,7 @@ class PlatformBackend(Backend):
         return result if isinstance(result, list) else result.get("results", [])
 
     def get_event(self, event_id: str) -> dict:
-        return self._request("GET", f"/v1/event/{event_id}/")
+        return self._request("GET", f"/v1/event/{_encode_path_segment(event_id)}/")
 
 
 class AuthError(Exception):
diff --git a/cli/python/tests/test_platform_backend_paths.py b/cli/python/tests/test_platform_backend_paths.py
new file mode 100644
index 000000000..5571dafa8
--- /dev/null
+++ b/cli/python/tests/test_platform_backend_paths.py
@@ -0,0 +1,43 @@
+from unittest.mock import MagicMock
+
+from mem0_cli.backend.platform import PlatformBackend
+
+
+def _backend(sample_config):
+    backend = PlatformBackend(sample_config.platform)
+    backend._client = MagicMock()
+    backend._client.request.return_value = MagicMock(
+        status_code=200,
+        json=lambda: {"message": "ok"},
+        headers={},
+        raise_for_status=lambda: None,
+    )
+    return backend
+
+
+def test_memory_id_path_segments_are_encoded(sample_config):
+    backend = _backend(sample_config)
+
+    backend.get("mem/a?b#c")
+    backend.update("mem/a?b#c", content="updated")
+    backend.delete("mem/a?b#c")
+
+    paths = [call.args[1] for call in backend._client.request.call_args_list]
+    assert paths == [
+        "/v1/memories/mem%2Fa%3Fb%23c/",
+        "/v1/memories/mem%2Fa%3Fb%23c/",
+        "/v1/memories/mem%2Fa%3Fb%23c/",
+    ]
+
+
+def test_entity_and_event_path_segments_are_encoded(sample_config):
+    backend = _backend(sample_config)
+
+    backend.delete_entities(user_id="org/team?active#frag")
+    backend.get_event("evt/a?b#c")
+
+    paths = [call.args[1] for call in backend._client.request.call_args_list]
+    assert paths == [
+        "/v2/entities/user/org%2Fteam%3Factive%23frag/",
+        "/v1/event/evt%2Fa%3Fb%23c/",
+    ]
diff --git a/mem0-ts/src/client/mem0.ts b/mem0-ts/src/client/mem0.ts
index 6d5f4c7e1..3fd19eb39 100644
--- a/mem0-ts/src/client/mem0.ts
+++ b/mem0-ts/src/client/mem0.ts
@@ -67,6 +67,10 @@ function rejectTopLevelEntityParams(
   }
 }
 
+function encodePathSegment(value: unknown): string {
+  return encodeURIComponent(String(value));
+}
+
 class APIError extends Error {
   constructor(message: string) {
     super(message);
@@ -311,7 +315,7 @@ export default class MemoryClient {
     this._captureEvent("update", [payloadKeys]);
 
     const response = await this._fetchWithErrorHandling(
-      `${this.host}/v1/memories/${memoryId}/`,
+      `${this.host}/v1/memories/${encodePathSegment(memoryId)}/`,
       {
         method: "PUT",
         headers: this.headers,
@@ -325,7 +329,7 @@ export default class MemoryClient {
     if (this.telemetryId === "") await this.ping();
     this._captureEvent("get", []);
     return this._fetchWithErrorHandling(
-      `${this.host}/v1/memories/${memoryId}/`,
+      `${this.host}/v1/memories/${encodePathSegment(memoryId)}/`,
       {
         headers: this.headers,
       },
@@ -397,7 +401,7 @@ export default class MemoryClient {
     // @ts-ignore
     const query = new URLSearchParams(snakeOptions).toString();
     return this._fetchWithErrorHandling(
-      `${this.host}/v1/memories/${memoryId}/${query ? `?${query}` : ""}`,
+      `${this.host}/v1/memories/${encodePathSegment(memoryId)}/${query ? `?${query}` : ""}`,
       {
         method: "DELETE",
         headers: this.headers,
@@ -428,7 +432,7 @@ export default class MemoryClient {
     if (this.telemetryId === "") await this.ping();
     this._captureEvent("history", []);
     const response = await this._fetchWithErrorHandling(
-      `${this.host}/v1/memories/${memoryId}/history/`,
+      `${this.host}/v1/memories/${encodePathSegment(memoryId)}/history/`,
       {
         headers: this.headers,
       },
@@ -466,7 +470,7 @@ export default class MemoryClient {
       data.entity_type = "user";
     }
     const response = await this._fetchWithErrorHandling(
-      `${this.host}/v1/entities/${data.entity_type}/${data.entity_id}/`,
+      `${this.host}/v1/entities/${encodePathSegment(data.entity_type)}/${encodePathSegment(data.entity_id)}/`,
       {
         method: "DELETE",
         headers: this.headers,
@@ -510,7 +514,9 @@ export default class MemoryClient {
 
     for (const entity of to_delete) {
       try {
-        await this.client.delete(`/v2/entities/${entity.type}/${entity.name}/`);
+        await this.client.delete(
+          `/v2/entities/${encodePathSegment(entity.type)}/${encodePathSegment(entity.name)}/`,
+        );
       } catch (error: any) {
         throw new APIError(
           `Failed to delete ${entity.type} ${entity.name}: ${error.message}`,
diff --git a/mem0-ts/src/client/tests/memoryClient.crud.test.ts b/mem0-ts/src/client/tests/memoryClient.crud.test.ts
index db2b20f65..f116955f1 100644
--- a/mem0-ts/src/client/tests/memoryClient.crud.test.ts
+++ b/mem0-ts/src/client/tests/memoryClient.crud.test.ts
@@ -118,6 +118,20 @@ describe("MemoryClient - get()", () => {
     const client = new MemoryClient({ apiKey: TEST_API_KEY });
     await expect(client.get("nonexistent")).rejects.toThrow("Memory not found");
   });
+
+  test("URL-encodes memory ID path segments", async () => {
+    const extra = new Map<string, { status: number; body: unknown }>();
+    extra.set("/v1/memories/mem%2Fa%3Fb%23c/", {
+      status: 200,
+      body: createMockMemory({ id: "mem/a?b#c" }),
+    });
+    const mock = setupMockFetch(extra);
+
+    const client = new MemoryClient({ apiKey: TEST_API_KEY });
+    await client.get("mem/a?b#c");
+
+    expect(findFetchCall(mock, "/v1/memories/mem%2Fa%3Fb%23c/")).toBeDefined();
+  });
 });
 
 // ─── update() ────────────────────────────────────────────
@@ -213,6 +227,22 @@ describe("MemoryClient - update()", () => {
       "At least one of text, metadata, timestamp, or expirationDate must be provided",
     );
   });
+
+  test("URL-encodes memory ID path segments", async () => {
+    const extra = new Map<string, { status: number; body: unknown }>();
+    extra.set("/v1/memories/mem%2Fa%3Fb%23c/", {
+      status: 200,
+      body: createMockMemory({ id: "mem/a?b#c" }),
+    });
+    const mock = setupMockFetch(extra);
+
+    const client = new MemoryClient({ apiKey: TEST_API_KEY });
+    await client.update("mem/a?b#c", { text: "Updated text" });
+
+    expect(
+      findFetchCall(mock, "/v1/memories/mem%2Fa%3Fb%23c/", "PUT"),
+    ).toBeDefined();
+  });
 });
 
 // ─── delete() ────────────────────────────────────────────
@@ -250,6 +280,22 @@ describe("MemoryClient - delete()", () => {
     expect(call).toBeDefined();
     expect(call![0]).toContain("delete_linked=true");
   });
+
+  test("URL-encodes memory ID path segments before adding query params", async () => {
+    const extra = new Map<string, { status: number; body: unknown }>();
+    extra.set("/v1/memories/mem%2Fa%3Fb%23c/", {
+      status: 200,
+      body: { message: "Memory deleted successfully" },
+    });
+    const mock = setupMockFetch(extra);
+
+    const client = new MemoryClient({ apiKey: TEST_API_KEY });
+    await client.delete("mem/a?b#c", { deleteLinked: true });
+
+    const call = findFetchCall(mock, "/v1/memories/mem%2Fa%3Fb%23c/", "DELETE");
+    expect(call).toBeDefined();
+    expect(call![0]).toContain("delete_linked=true");
+  });
 });
 
 // ─── deleteAll() ─────────────────────────────────────────
@@ -326,4 +372,23 @@ describe("MemoryClient - history()", () => {
     const result: MemoryHistory[] = await client.history("mem_123");
     expect(result).toEqual([]);
   });
+
+  test("URL-encodes memory ID path segments", async () => {
+    const historyEntries = [
+      createMockMemoryHistory({ memory_id: "mem/a?b#c" }),
+    ];
+    const extra = new Map<string, { status: number; body: unknown }>();
+    extra.set("/v1/memories/mem%2Fa%3Fb%23c/history/", {
+      status: 200,
+      body: historyEntries,
+    });
+    const mock = setupMockFetch(extra);
+
+    const client = new MemoryClient({ apiKey: TEST_API_KEY });
+    await client.history("mem/a?b#c");
+
+    expect(
+      findFetchCall(mock, "/v1/memories/mem%2Fa%3Fb%23c/history/"),
+    ).toBeDefined();
+  });
 });
diff --git a/mem0-ts/src/client/tests/memoryClient.users.test.ts b/mem0-ts/src/client/tests/memoryClient.users.test.ts
index ba232f21c..5cdb30294 100644
--- a/mem0-ts/src/client/tests/memoryClient.users.test.ts
+++ b/mem0-ts/src/client/tests/memoryClient.users.test.ts
@@ -71,4 +71,43 @@ describe("MemoryClient - deleteUser() (deprecated)", () => {
       findFetchCall(mock, "/v1/entities/user/456/", "DELETE"),
     ).toBeDefined();
   });
+
+  test("URL-encodes entity path segments", async () => {
+    const extra = new Map<string, { status: number; body: unknown }>();
+    extra.set("/v1/entities/team%2Ftype/org%2Fteam%3Factive%23frag/", {
+      status: 200,
+      body: { message: "Entity deleted successfully!" },
+    });
+    const mock = setupMockFetch(extra);
+
+    const client = new MemoryClient({ apiKey: TEST_API_KEY });
+    await client.deleteUser({
+      entity_id: "org/team?active#frag" as never,
+      entity_type: "team/type",
+    });
+
+    expect(
+      findFetchCall(
+        mock,
+        "/v1/entities/team%2Ftype/org%2Fteam%3Factive%23frag/",
+        "DELETE",
+      ),
+    ).toBeDefined();
+  });
+});
+
+describe("MemoryClient - deleteUsers()", () => {
+  test("URL-encodes entity path segments", async () => {
+    setupMockFetch();
+    const client = new MemoryClient({ apiKey: TEST_API_KEY });
+    client.telemetryId = "test@example.com";
+    const deleteMock = jest.fn().mockResolvedValue({});
+    client.client = { delete: deleteMock };
+
+    await client.deleteUsers({ userId: "org/team?active#frag" });
+
+    expect(deleteMock).toHaveBeenCalledWith(
+      "/v2/entities/user/org%2Fteam%3Factive%23frag/",
+    );
+  });
 });
diff --git a/mem0/client/main.py b/mem0/client/main.py
index c26aa7231..853a8588d 100644
--- a/mem0/client/main.py
+++ b/mem0/client/main.py
@@ -3,6 +3,7 @@ import logging
 import os
 import warnings
 from typing import Any, Dict, List, Optional
+from urllib.parse import quote
 
 import httpx
 import requests
@@ -42,6 +43,10 @@ def _validate_and_trim_search_query(query: str) -> str:
     return trimmed
 
 
+def _encode_path_segment(value: Any) -> str:
+    return quote(str(value), safe="")
+
+
 def _maybe_alias_anon_to_email(user_email):
     """Fire $identify per prior anon ID so PostHog merges them into email.
 
@@ -229,7 +234,7 @@ class MemoryClient:
             MemoryNotFoundError: If the memory doesn't exist (for updates/deletes).
         """
         params = self._prepare_params()
-        response = self.client.get(f"/v1/memories/{memory_id}/", params=params)
+        response = self.client.get(f"/v1/memories/{_encode_path_segment(memory_id)}/", params=params)
         response.raise_for_status()
         capture_client_event("client.get", self, {"memory_id": memory_id, "sync_type": "sync"})
         return response.json()
@@ -367,7 +372,7 @@ class MemoryClient:
 
         capture_client_event("client.update", self, {"memory_id": memory_id, "sync_type": "sync"})
         params = self._prepare_params()
-        response = self.client.put(f"/v1/memories/{memory_id}/", json=payload, params=params)
+        response = self.client.put(f"/v1/memories/{_encode_path_segment(memory_id)}/", json=payload, params=params)
         response.raise_for_status()
         return response.json()
 
@@ -395,7 +400,7 @@ class MemoryClient:
             MemoryNotFoundError: If the memory doesn't exist (for updates/deletes).
         """
         params = self._prepare_params({"delete_linked": delete_linked or None})
-        response = self.client.delete(f"/v1/memories/{memory_id}/", params=params)
+        response = self.client.delete(f"/v1/memories/{_encode_path_segment(memory_id)}/", params=params)
         response.raise_for_status()
         capture_client_event(
             "client.delete", self, {"memory_id": memory_id, "delete_linked": delete_linked, "sync_type": "sync"}
@@ -452,7 +457,7 @@ class MemoryClient:
             MemoryNotFoundError: If the memory doesn't exist (for updates/deletes).
         """
         params = self._prepare_params()
-        response = self.client.get(f"/v1/memories/{memory_id}/history/", params=params)
+        response = self.client.get(f"/v1/memories/{_encode_path_segment(memory_id)}/history/", params=params)
         response.raise_for_status()
         capture_client_event("client.history", self, {"memory_id": memory_id, "sync_type": "sync"})
         return response.json()
@@ -513,7 +518,10 @@ class MemoryClient:
 
         # Delete entities and check response immediately
         for entity in to_delete:
-            response = self.client.delete(f"/v2/entities/{entity['type']}/{entity['name']}/", params=params)
+            response = self.client.delete(
+                f"/v2/entities/{_encode_path_segment(entity['type'])}/{_encode_path_segment(entity['name'])}/",
+                params=params,
+            )
             response.raise_for_status()
 
         capture_client_event(
@@ -691,7 +699,9 @@ class MemoryClient:
             ValueError: If org_id or project_id are not set.
         """
         logger.warning(
-            "get_project() method is going to be deprecated in version v1.0 of the package. Please use the client.project.get() method instead."
+            "get_project() method is going to be deprecated in version v1.0 "
+            "of the package. Please use the client.project.get() method "
+            "instead."
         )
         if not (self.org_id and self.project_id):
             raise ValueError("org_id and project_id must be set to access instructions or categories")
@@ -1147,7 +1157,7 @@ class AsyncMemoryClient:
     @api_error_handler
     async def get(self, memory_id: str) -> Dict[str, Any]:
         params = self._prepare_params()
-        response = await self.async_client.get(f"/v1/memories/{memory_id}/", params=params)
+        response = await self.async_client.get(f"/v1/memories/{_encode_path_segment(memory_id)}/", params=params)
         response.raise_for_status()
         capture_client_event("client.get", self, {"memory_id": memory_id, "sync_type": "async"})
         return response.json()
@@ -1285,7 +1295,9 @@ class AsyncMemoryClient:
 
         capture_client_event("client.update", self, {"memory_id": memory_id, "sync_type": "async"})
         params = self._prepare_params()
-        response = await self.async_client.put(f"/v1/memories/{memory_id}/", json=payload, params=params)
+        response = await self.async_client.put(
+            f"/v1/memories/{_encode_path_segment(memory_id)}/", json=payload, params=params
+        )
         response.raise_for_status()
         return response.json()
 
@@ -1313,7 +1325,7 @@ class AsyncMemoryClient:
             MemoryNotFoundError: If the memory doesn't exist (for updates/deletes).
         """
         params = self._prepare_params({"delete_linked": delete_linked or None})
-        response = await self.async_client.delete(f"/v1/memories/{memory_id}/", params=params)
+        response = await self.async_client.delete(f"/v1/memories/{_encode_path_segment(memory_id)}/", params=params)
         response.raise_for_status()
         capture_client_event(
             "client.delete", self, {"memory_id": memory_id, "delete_linked": delete_linked, "sync_type": "async"}
@@ -1365,7 +1377,10 @@ class AsyncMemoryClient:
             MemoryNotFoundError: If the memory doesn't exist (for updates/deletes).
         """
         params = self._prepare_params()
-        response = await self.async_client.get(f"/v1/memories/{memory_id}/history/", params=params)
+        response = await self.async_client.get(
+            f"/v1/memories/{_encode_path_segment(memory_id)}/history/",
+            params=params,
+        )
         response.raise_for_status()
         capture_client_event("client.history", self, {"memory_id": memory_id, "sync_type": "async"})
         return response.json()
@@ -1426,7 +1441,10 @@ class AsyncMemoryClient:
 
         # Delete entities and check response immediately
         for entity in to_delete:
-            response = await self.async_client.delete(f"/v2/entities/{entity['type']}/{entity['name']}/", params=params)
+            response = await self.async_client.delete(
+                f"/v2/entities/{_encode_path_segment(entity['type'])}/{_encode_path_segment(entity['name'])}/",
+                params=params,
+            )
             response.raise_for_status()
 
         capture_client_event(
@@ -1590,7 +1608,9 @@ class AsyncMemoryClient:
             ValueError: If org_id or project_id are not set.
         """
         logger.warning(
-            "get_project() method is going to be deprecated in version v1.0 of the package. Please use the client.project.get() method instead."
+            "get_project() method is going to be deprecated in version v1.0 "
+            "of the package. Please use the client.project.get() method "
+            "instead."
         )
         if not (self.org_id and self.project_id):
             raise ValueError("org_id and project_id must be set to access instructions or categories")
diff --git a/tests/test_client.py b/tests/test_client.py
index 2c5934575..8aa554763 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -1,7 +1,8 @@
 """Tests for MemoryClient entity parameter rejection."""
 
+import asyncio
 import json
-from unittest.mock import MagicMock, patch
+from unittest.mock import AsyncMock, MagicMock, patch
 
 import httpx
 import pytest
@@ -259,6 +260,84 @@ class TestDeleteLinked:
         assert "delete_linked" not in call_args.kwargs.get("params", {})
 
 
+class TestPathSegmentEncoding:
+    """Path params should remain one URL segment even when IDs contain URL syntax."""
+
+    def _setup_response(self):
+        return MagicMock(json=lambda: {"message": "ok"}, raise_for_status=lambda: None)
+
+    def _called_paths(self, mock_method):
+        return [call.args[0] for call in mock_method.call_args_list]
+
+    def test_sync_memory_id_path_segments_are_encoded(self, mock_memory_client):
+        mock_memory_client.client.get.return_value = self._setup_response()
+        mock_memory_client.client.put.return_value = self._setup_response()
+        mock_memory_client.client.delete.return_value = self._setup_response()
+
+        memory_id = "mem/a?b#c"
+
+        mock_memory_client.get(memory_id)
+        mock_memory_client.update(memory_id, text="updated")
+        mock_memory_client.delete(memory_id)
+        mock_memory_client.history(memory_id)
+
+        assert "/v1/memories/mem%2Fa%3Fb%23c/" in self._called_paths(mock_memory_client.client.get)
+        assert mock_memory_client.client.put.call_args.args[0] == "/v1/memories/mem%2Fa%3Fb%23c/"
+        assert mock_memory_client.client.delete.call_args.args[0] == "/v1/memories/mem%2Fa%3Fb%23c/"
+        assert "/v1/memories/mem%2Fa%3Fb%23c/history/" in self._called_paths(mock_memory_client.client.get)
+
+    def test_sync_entity_path_segments_are_encoded(self, mock_memory_client):
+        mock_memory_client.client.delete.return_value = self._setup_response()
+
+        mock_memory_client.delete_users(user_id="org/team?active#frag")
+
+        assert mock_memory_client.client.delete.call_args.args[0] == (
+            "/v2/entities/user/org%2Fteam%3Factive%23frag/"
+        )
+
+    def test_async_memory_id_path_segments_are_encoded(self):
+        asyncio.run(self._assert_async_memory_id_path_segments_are_encoded())
+
+    async def _assert_async_memory_id_path_segments_are_encoded(self):
+        from mem0.client.main import AsyncMemoryClient
+
+        client = AsyncMemoryClient.__new__(AsyncMemoryClient)
+        client.async_client = MagicMock()
+        client.async_client.get = AsyncMock(return_value=self._setup_response())
+        client.async_client.put = AsyncMock(return_value=self._setup_response())
+        client.async_client.delete = AsyncMock(return_value=self._setup_response())
+
+        memory_id = "mem/a?b#c"
+
+        with patch("mem0.client.main.capture_client_event"):
+            await client.get(memory_id)
+            await client.update(memory_id, text="updated")
+            await client.delete(memory_id)
+            await client.history(memory_id)
+
+        assert client.async_client.get.call_args_list[0].args[0] == "/v1/memories/mem%2Fa%3Fb%23c/"
+        assert client.async_client.put.call_args.args[0] == "/v1/memories/mem%2Fa%3Fb%23c/"
+        assert client.async_client.delete.call_args.args[0] == "/v1/memories/mem%2Fa%3Fb%23c/"
+        assert client.async_client.get.call_args_list[1].args[0] == "/v1/memories/mem%2Fa%3Fb%23c/history/"
+
+    def test_async_entity_path_segments_are_encoded(self):
+        asyncio.run(self._assert_async_entity_path_segments_are_encoded())
+
+    async def _assert_async_entity_path_segments_are_encoded(self):
+        from mem0.client.main import AsyncMemoryClient
+
+        client = AsyncMemoryClient.__new__(AsyncMemoryClient)
+        client.async_client = MagicMock()
+        client.async_client.delete = AsyncMock(return_value=self._setup_response())
+
+        with patch("mem0.client.main.capture_client_event"):
+            await client.delete_users(user_id="org/team?active#frag")
+
+        assert client.async_client.delete.call_args.args[0] == (
+            "/v2/entities/user/org%2Fteam%3Factive%23frag/"
+        )
+
+
 class TestValidateApiKeyHttpError:
     """_validate_api_key should surface a clear ValueError on a non-JSON HTTP error.