diff --git a/backend/src/controllers/userController.js b/backend/src/controllers/userController.js
index de10150..548661d 100644
--- a/backend/src/controllers/userController.js
+++ b/backend/src/controllers/userController.js
@@ -1,3 +1,4 @@
+import User from "../models/User.js";
 export const authMe = async (req, res) => {
   try {
     const user = req.user; // lấy từ authMiddleware
@@ -9,4 +10,20 @@ export const authMe = async (req, res) => {
     console.error("Lỗi khi gọi authMe", error);
     return res.status(500).json({ message: "Lỗi hệ thống" });
   }
-};
\ No newline at end of file
+};
+
+export const searchUserByUserName = async (req, res) => {
+  try {
+    const {username} = req.query;
+    if(!username || username.trim() === ""){
+      return res.status(400).json({message:"Hay nhap username"})
+    }
+
+    const user = await User.findOne({username}).select("_id displayName userName avartarUrl");
+
+    return res.status(200).json({user});
+  } catch (error) {
+      console.error("Loi xay ra khi search user by username:",error);
+      return res.status(500).json({message:"Loi he thong"})
+  }
+};
diff --git a/backend/src/routes/userRoute.js b/backend/src/routes/userRoute.js
index c359aba..bc3c447 100644
--- a/backend/src/routes/userRoute.js
+++ b/backend/src/routes/userRoute.js
@@ -1,8 +1,9 @@
 import express from "express";
-import { authMe } from "../controllers/userController.js";
+import { authMe, searchUserByUserName } from "../controllers/userController.js";
 
 const router = express.Router();
 
 router.get("/me", authMe);
+router.get("/search",searchUserByUserName)
 
 export default router;
\ No newline at end of file
diff --git a/frontend/src/components/AddFriendModal/SearchForm.tsx b/frontend/src/components/AddFriendModal/SearchForm.tsx
new file mode 100644
index 0000000..7ab45f8
--- /dev/null
+++ b/frontend/src/components/AddFriendModal/SearchForm.tsx
@@ -0,0 +1,94 @@
+import type { FieldErrors, UseFormRegister } from "react-hook-form";
+import type { IFormValues } from "../chat/modals/AddFriendModal";
+import { Label } from "../ui/label";
+import { Input } from "../ui/input";
+import { DialogClose, DialogFooter } from "../ui/dialog";
+import { Button } from "../ui/button";
+import { LoaderIcon, Search } from "lucide-react";
+
+interface SearchFormProps {
+  register: UseFormRegister<IFormValues>;
+  errors: FieldErrors<IFormValues>;
+  loading: boolean;
+  usernameValue: string;
+  isFound: boolean | null;
+  searchedUsername: string;
+  onSubmit?: (e: React.FormEvent<HTMLFormElement>) => void;
+  onCancel: () => void;
+}
+
+const SearchForm = ({
+  register,
+  errors,
+  loading,
+  usernameValue,
+  isFound,
+  searchedUsername,
+  onSubmit,
+  onCancel,
+}: SearchFormProps) => {
+  return (
+    <form onSubmit={onSubmit} className="space-y-4 ">
+      <div className="space-y-2">
+        <Label htmlFor="username" className="text-sm font-semiblod">
+          Tìm bằng username
+        </Label>
+        <Input
+          id="username"
+          placeholder="Nhập username để kết bạn"
+          className="glass border-border/50 focus:border-primary/50 transition-smooth"
+          {...register("username", {
+            required: "Username không được bỏ trống",
+          })}
+        ></Input>
+        {errors.username && (
+          <p className="text-sm text-destructive">{errors.username.message}</p>
+        )}
+
+        {isFound === false && (
+          <span className="text-sm text-destructive">
+            Không tìm thấy người dùng
+            <span className="font-semibold">@{searchedUsername}</span>
+          </span>
+        )}
+      </div>
+
+      <DialogFooter>
+        <DialogClose>
+          <Button
+            type="button"
+            variant={"outline"}
+            className={"flex-1 glass hover:text-destructive"}
+            onClick={onCancel}
+          >
+            Hủy
+          </Button>
+        </DialogClose>
+
+        <Button
+          type="submit"
+          disabled={loading || !usernameValue?.trim()}
+          className={
+            "flex-1 bg-gradient-chat text-white hover:opacity-90 transition-smooth "
+          }
+        >
+          {loading ? (
+            <>
+              <LoaderIcon
+                role="status"
+                aria-label="Loading"
+                className="size-4 animate-spin dark:text-white"
+              />
+            </>
+          ) : (
+            <>
+              <Search className="size-4 mr-2" />
+            </>
+          )}
+        </Button>
+      </DialogFooter>
+    </form>
+  );
+};
+
+export default SearchForm;
diff --git a/frontend/src/components/AddFriendModal/SendFriendRequest.tsx b/frontend/src/components/AddFriendModal/SendFriendRequest.tsx
new file mode 100644
index 0000000..47f0f3e
--- /dev/null
+++ b/frontend/src/components/AddFriendModal/SendFriendRequest.tsx
@@ -0,0 +1,76 @@
+import type { UseFormRegister } from "react-hook-form";
+import type { IFormValues } from "../chat/modals/AddFriendModal";
+import { Label } from "../ui/label";
+import { Textarea } from "../ui/textarea";
+import { DialogFooter } from "../ui/dialog";
+import { Button } from "../ui/button";
+import { LoaderIcon, UserPlus } from "lucide-react";
+
+interface SendRequestProps {
+  register: UseFormRegister<IFormValues>;
+  loading: boolean;
+  searchedUserName: string;
+  onSubmit?: (e: React.FormEvent<HTMLFormElement>) => void;
+  onBack: () => void;
+}
+const SendFriendRequest = ({
+  register,
+  loading,
+  searchedUserName,
+  onSubmit,
+  onBack,
+}: SendRequestProps) => {
+  return (
+    <form onSubmit={onSubmit}>
+    <div  className="space-y-4">
+      <span className="success-message">
+        Đã tìm thấy<span className="font-semibold">@{searchedUserName}</span>
+      </span>
+      <div className="space-y-2">
+        <Label htmlFor="message" className="text-sm font-semibold">
+          Giới thiệu
+        </Label>
+        <Textarea
+          id="message"
+          rows={3}
+          placeholder="Chào bạn, có thể kết bạn được không?"
+          className="glass border-border/50 focus:border-primary/50 transition-smooth resize-none"
+          {...register("message")}
+        />
+      </div>
+      <DialogFooter>
+        <Button
+          type="button"
+          variant={"outline"}
+          className={"flex-1 glass hover:text-destructive"}
+          onClick={onBack}
+        >
+          Quay lại
+        </Button>
+        <Button
+          type="submit"
+          disabled={loading}
+          className={
+            "flex-1 bg-gradient-chat text-white hover:opacity-90 transition-smooth"
+          }
+        >
+          {loading ? (
+            <>
+              <LoaderIcon
+                role="status"
+                aria-label="Loading"
+                className="size-4 animate-spin dark:text-white"
+              />
+            </>
+          ) : (
+            <>
+              <UserPlus className="size-4 mr-2" /> Kết bạn
+            </>
+          )}
+        </Button>
+      </DialogFooter>
+    </div>
+  </form>)
+};
+
+export default SendFriendRequest;
diff --git a/frontend/src/components/auth/ProtectedRoute.tsx b/frontend/src/components/auth/ProtectedRoute.tsx
index 1af6506..0864a7e 100644
--- a/frontend/src/components/auth/ProtectedRoute.tsx
+++ b/frontend/src/components/auth/ProtectedRoute.tsx
@@ -2,7 +2,6 @@ import { useAuthStore } from "@/stores/useAuthStore";
 import { useEffect, useRef, useState } from "react";
 import { Navigate, Outlet } from "react-router";
 import { LoaderIcon } from "lucide-react";
-import { cn } from "@/lib/utils";
 
 const ProtectedRoute = () => {
   const { accessToken, user, loading, refresh, fetchMe, clearState } =
diff --git a/frontend/src/components/chat/modals/AddFriendModal.tsx b/frontend/src/components/chat/modals/AddFriendModal.tsx
index cb5b84b..b5b7c01 100644
--- a/frontend/src/components/chat/modals/AddFriendModal.tsx
+++ b/frontend/src/components/chat/modals/AddFriendModal.tsx
@@ -1,7 +1,125 @@
+import SearchForm from "@/components/AddFriendModal/SearchForm";
+import SendFriendRequest from "@/components/AddFriendModal/SendFriendRequest";
+import {
+  Dialog,
+  DialogContent,
+  DialogHeader,
+  DialogTitle,
+  DialogTrigger,
+} from "@/components/ui/dialog";
+import { useFriendStore } from "@/stores/useFriendRequest";
+import type { User } from "@/types/user";
+import { UserPlus } from "lucide-react";
+import { useState } from "react";
+import { useForm } from "react-hook-form";
+import { toast } from "sonner";
+
+export interface IFormValues {
+  username: string;
+  message: string;
+}
+
 const AddFriendModal = () => {
+  const [isFound, setIsFound] = useState<boolean | null>(null);
+  const [searchUser, setSearchUser] = useState<User>();
+  const [searchedUserName, setsearchedUserName] = useState("");
+  const { loading, searchByUserName, addFriend } = useFriendStore();
+
+  const {
+    register,
+    handleSubmit,
+    watch,
+    reset,
+    formState: { errors },
+  } = useForm<IFormValues>({
+    defaultValues: { username: "", message: "" },
+  });
+
+  const usernameValue = watch("username");
+
+  const handleSearch = handleSubmit(async (data) => {
+    const username = data.username.trim();
+    if (!username) return;
+
+    setIsFound(null);
+    setsearchedUserName(username);
+
+    try {
+      const foundUser = await searchByUserName(username);
+
+      if (foundUser) {
+        setIsFound(true);
+        setSearchUser(foundUser);
+      } else {
+        setIsFound(false);
+      }
+    } catch (error) {
+      console.error(error);
+      setIsFound(false);
+    }
+  });
+
+  const handleSend = handleSubmit(async (data) => {
+    if (!searchUser) return;
+    try {
+      const message = await addFriend(searchUser._id, data.message.trim());
+      toast.success(message);
+      handleCancel();
+    } catch (error) {
+      console.error("Lỗi xảy ra khi gửi request từ form:", error);
+    }
+  });
+
+  const handleCancel = () => {
+    reset();
+    setsearchedUserName("");
+    setIsFound(null);
+  };
+
   return (
-    <div>AddFriendModal</div>
-  )
-}
+    <Dialog>
+      <DialogTrigger>
+        <div
+          className="flex justify-center items-center size-5
+          rounded-full hover:bg-sidebar-accent cursor-pointer z-10"
+        >
+          <UserPlus className="size-4" />
+          <span className="sr-only">Kết bạn</span>
+        </div>
+      </DialogTrigger>
+
+      <DialogContent className={"sm:max-w-[425px] border-none"}>
+        <DialogHeader>
+          <DialogTitle>Kết bạn</DialogTitle>
+        </DialogHeader>
+        {!isFound && (
+          <>
+            <SearchForm
+              register={register}
+              errors={errors}
+              usernameValue={usernameValue}
+              loading={loading}
+              isFound={isFound}
+              searchedUsername={searchedUserName}
+              onSubmit={handleSearch}
+              onCancel={handleCancel}
+            />
+          </>
+        )}
+        {isFound && (
+          <>
+            <SendFriendRequest
+              register={register}
+              loading={loading}
+              searchedUserName={searchedUserName}
+              onSubmit={handleSend}
+              onBack={() => setIsFound(null)}
+            />
+          </>
+        )}
+      </DialogContent>
+    </Dialog>
+  );
+};
 
-export default AddFriendModal
\ No newline at end of file
+export default AddFriendModal;
diff --git a/frontend/src/index.css b/frontend/src/index.css
index def5c18..da41417 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -286,6 +286,11 @@
     dark:scrollbar-thumb-slate-600;
   }
 
+  .success-message{
+    @apply text-sm text-emerald-500
+  }
+
+
   /* Animations */
   .transition-bounce {
     transition: var(--transition-bounce);
diff --git a/frontend/src/services/friendService.ts b/frontend/src/services/friendService.ts
new file mode 100644
index 0000000..7e098ff
--- /dev/null
+++ b/frontend/src/services/friendService.ts
@@ -0,0 +1,14 @@
+import api from "@/lib/axios";
+
+export const friendService = {
+
+    async searchByUserName(username:string){
+        const res = await api.get(`/users/search?username=${username}`);
+        return res.data.user;
+    },
+
+    async sendFriendRequest(to:string,message?:string){
+        const res = await api.post("/friend/request",{to,message});
+        return res.data.message;
+    }
+}
\ No newline at end of file
diff --git a/frontend/src/stores/useFriendRequest.ts b/frontend/src/stores/useFriendRequest.ts
new file mode 100644
index 0000000..a3fee1d
--- /dev/null
+++ b/frontend/src/stores/useFriendRequest.ts
@@ -0,0 +1,33 @@
+import { friendService } from "@/services/friendService";
+import type { FriendState } from "@/types/store";
+import { create } from "zustand";
+
+export const useFriendStore = create<FriendState>((set, get) => ({
+  loading: false,
+  searchByUserName: async (username) => {
+    try {
+      set({ loading: true });
+
+      const user = await friendService.searchByUserName(username);
+
+      return user;
+    } catch (error) {
+      console.error("Loi xay ra khi tim user bawng username:", error);
+      return null;
+    } finally {
+      set({ loading: false });
+    }
+  },
+  addFriend: async (to, message) => {
+    try {
+      set({ loading: true });
+      const result = await friendService.sendFriendRequest(to, message);
+      return result;
+    } catch (error) {
+      console.error("Loi xay ra khi add Friend:", error);
+      return "Lỗi xảy ra khi gửi kết bạn hãy thử lại"
+    } finally {
+      set({ loading: false });
+    }
+  },
+}));
diff --git a/frontend/src/types/store.ts b/frontend/src/types/store.ts
index 1be6fc4..6435582 100644
--- a/frontend/src/types/store.ts
+++ b/frontend/src/types/store.ts
@@ -58,4 +58,10 @@ export interface SocketState{
   onlineUsers: string[];
   connectSocket: () => void;
   disconnectSocket: () => void;
+}
+
+export interface FriendState{
+  loading:boolean;
+  searchByUserName:(username:string) => Promise<User | null>;
+  addFriend:(to:string,message?:string) => Promise<string>;
 }
\ No newline at end of file