diff --git a/backend/README.md b/backend/README.md
index c999365..8b3b9a3 100644
--- a/backend/README.md
+++ b/backend/README.md
@@ -87,6 +87,27 @@ Health endpoint:
 curl http://localhost:5000/api/health
 ```
 
+## Discovery Swipe Filtering
+
+`GET /api/foods/discover` supports filtering out previously swiped food items.
+
+Query params:
+
+- `longitude` (required)
+- `latitude` (required)
+- `cursor` (optional)
+- `user_id` (optional; when present, excludes swiped food for that user)
+
+`UserSwipe` model fields:
+
+- `user_id`
+- `food_id`
+- `action` (`like` | `pass`)
+- `timestamp`
+
+Index:
+
+- compound index on `{ user_id: 1, food_id: 1 }`
 ## Discovery Endpoint
 
 `GET /api/foods/discover`
diff --git a/backend/src/routes/foods.routes.ts b/backend/src/routes/foods.routes.ts
index 9082aed..ffc47c4 100644
--- a/backend/src/routes/foods.routes.ts
+++ b/backend/src/routes/foods.routes.ts
@@ -1,12 +1,16 @@
 import { Router } from "express"
-import type { PipelineStage } from "mongoose"
+import { Types, type PipelineStage } from "mongoose"
 import { z } from "zod"
-import { RestaurantModel } from "../models/index.js"
+import { RestaurantModel, UserSwipeModel } from "../models/index.js"
 
 const querySchema = z.object({
   longitude: z.coerce.number(),
   latitude: z.coerce.number(),
   cursor: z.string().optional(),
+  user_id: z
+    .string()
+    .refine((value) => Types.ObjectId.isValid(value), "user_id must be a valid ObjectId")
+    .optional(),
 })
 
 const PAGE_SIZE = 10
@@ -49,6 +53,7 @@ export const foodsRouter = Router()
 foodsRouter.get("/discover", async (req, res, next) => {
   try {
     const query = querySchema.parse(req.query)
+
     let skip = 0
     try {
       skip = decodeCursor(query.cursor)
@@ -60,6 +65,10 @@ foodsRouter.get("/discover", async (req, res, next) => {
       return
     }
 
+    const swipedFoodIds = query.user_id
+      ? await UserSwipeModel.distinct("food_id", { user_id: new Types.ObjectId(query.user_id) })
+      : []
+
     const pipeline: PipelineStage[] = [
       {
         $geoNear: {
@@ -81,14 +90,11 @@ foodsRouter.get("/discover", async (req, res, next) => {
           as: "foods",
         },
       },
-      {
-        $unwind: "$foods",
-      },
-      {
-        $match: {
-          "foods.is_active": true,
-        },
-      },
+      { $unwind: "$foods" },
+      { $match: { "foods.is_active": true } },
+      ...(swipedFoodIds.length > 0
+        ? ([{ $match: { "foods._id": { $nin: swipedFoodIds } } }] as PipelineStage[])
+        : []),
       {
         $project: {
           food_id: "$foods._id",
diff --git a/backend/test/foods-discover-swipe-filter.test.ts b/backend/test/foods-discover-swipe-filter.test.ts
new file mode 100644
index 0000000..b9f322d
--- /dev/null
+++ b/backend/test/foods-discover-swipe-filter.test.ts
@@ -0,0 +1,88 @@
+import assert from "node:assert/strict"
+import test from "node:test"
+import request from "supertest"
+import { RestaurantModel, UserSwipeModel } from "../src/models/index.js"
+import { createApp } from "../src/app.js"
+
+test("GET /api/foods/discover excludes swiped food ids when user_id is provided", async () => {
+  const app = createApp()
+
+  const originalDistinct = UserSwipeModel.distinct
+  const originalAggregate = RestaurantModel.aggregate
+
+  let capturedPipeline: Record<string, unknown>[] = []
+
+  ;(UserSwipeModel.distinct as unknown as (...args: unknown[]) => Promise<unknown>) = async () => [
+    "660000000000000000000500",
+  ]
+  ;(RestaurantModel.aggregate as unknown as (...args: unknown[]) => Promise<unknown>) = async (
+    pipeline: Record<string, unknown>[],
+  ) => {
+    capturedPipeline = pipeline
+    return []
+  }
+
+  const response = await request(app).get(
+    "/api/foods/discover?longitude=-73.99&latitude=40.73&user_id=660000000000000000000001",
+  )
+
+  assert.equal(response.status, 200)
+  assert.ok(
+    capturedPipeline.some((stage) => {
+      const match = stage.$match as Record<string, unknown> | undefined
+      const foods = match?.["foods._id"] as { $nin?: unknown[] } | undefined
+      return Array.isArray(foods?.$nin)
+    }),
+  )
+
+  UserSwipeModel.distinct = originalDistinct
+  RestaurantModel.aggregate = originalAggregate
+})
+
+test("GET /api/foods/discover does not apply swipe exclusion without user_id", async () => {
+  const app = createApp()
+
+  const originalDistinct = UserSwipeModel.distinct
+  const originalAggregate = RestaurantModel.aggregate
+
+  let distinctCalls = 0
+  let capturedPipeline: Record<string, unknown>[] = []
+
+  ;(UserSwipeModel.distinct as unknown as (...args: unknown[]) => Promise<unknown>) = async () => {
+    distinctCalls += 1
+    return []
+  }
+  ;(RestaurantModel.aggregate as unknown as (...args: unknown[]) => Promise<unknown>) = async (
+    pipeline: Record<string, unknown>[],
+  ) => {
+    capturedPipeline = pipeline
+    return []
+  }
+
+  const response = await request(app).get("/api/foods/discover?longitude=-73.99&latitude=40.73")
+
+  assert.equal(response.status, 200)
+  assert.equal(distinctCalls, 0)
+  assert.equal(
+    capturedPipeline.some((stage) => {
+      const match = stage.$match as Record<string, unknown> | undefined
+      return Boolean(match?.["foods._id"])
+    }),
+    false,
+  )
+
+  UserSwipeModel.distinct = originalDistinct
+  RestaurantModel.aggregate = originalAggregate
+})
+
+test("GET /api/foods/discover returns 400 when user_id is not a valid ObjectId", async () => {
+  const app = createApp()
+
+  const response = await request(app).get(
+    "/api/foods/discover?longitude=-73.99&latitude=40.73&user_id=invalid-id",
+  )
+
+  assert.equal(response.status, 400)
+  assert.equal(response.body.error, "Bad Request")
+  assert.equal(response.body.message, "Invalid query parameters")
+})