diff --git a/frontend/src/resources/css/_chat.scss b/frontend/src/resources/css/_chat.scss
index 479e739..42f54e7 100644
--- a/frontend/src/resources/css/_chat.scss
+++ b/frontend/src/resources/css/_chat.scss
@@ -340,3 +340,25 @@
     }
 }
 
+.message-profile-pic {
+    img {
+        width: 40px;
+        height: 40px;
+        border-radius: 50%;
+        object-fit: cover;
+        border: 2px solid $color-dark-outline;
+        
+        &.loading {
+            opacity: 0.6;
+            cursor: default;
+        }
+    }
+}
+
+.message-username {
+    &.loading {
+        opacity: 0.6;
+        cursor: default;
+    }
+}
+
diff --git a/frontend/src/resources/css/_profile.scss b/frontend/src/resources/css/_profile.scss
index 518c983..f3f60a4 100644
--- a/frontend/src/resources/css/_profile.scss
+++ b/frontend/src/resources/css/_profile.scss
@@ -187,6 +187,16 @@
                 }
             }
         }
+
+        .profile-actions {
+            display: flex;
+            gap: 0.75rem;
+            margin-top: 0.5rem;
+
+            mdui-button {
+                flex: 1;
+            }
+        }
     }
 }
 
diff --git a/frontend/src/ui/api/profileApi.ts b/frontend/src/ui/api/profileApi.ts
index a60f820..32a4b61 100644
--- a/frontend/src/ui/api/profileApi.ts
+++ b/frontend/src/ui/api/profileApi.ts
@@ -1,5 +1,6 @@
 import { getAuthHeaders } from "../../auth/api";
 import { API_BASE_URL } from "../../core/config";
+import type { UserProfile } from "../../core/types";
 
 export interface ProfileData {
     profile_picture?: string;
@@ -90,3 +91,23 @@ export async function updateBio(token: string, bio: string): Promise<boolean> {
         return false;
     }
 }
+
+/**
+ * Fetches user profile data by username
+ */
+export async function fetchUserProfile(token: string, username: string): Promise<UserProfile | null> {
+    try {
+        const response = await fetch(`${API_BASE_URL}/user/${username}`, {
+            headers: getAuthHeaders(token)
+        });
+
+        if (response.ok) {
+            return await response.json();
+        }
+        
+        return null;
+    } catch (error) {
+        console.error('Error fetching user profile:', error);
+        return null;
+    }
+}
diff --git a/frontend/src/ui/components/chat/ChatMessages.tsx b/frontend/src/ui/components/chat/ChatMessages.tsx
index 16e773a..cee6d0d 100644
--- a/frontend/src/ui/components/chat/ChatMessages.tsx
+++ b/frontend/src/ui/components/chat/ChatMessages.tsx
@@ -2,14 +2,34 @@ import { useChat } from "../../hooks/useChat";
 import { Message } from "./Message";
 import { useAppState } from "../../state";
 import type { Message as MessageType } from "../../../core/types";
+import type { UserProfile } from "../../../core/types";
+import { UserProfileDialog } from "./UserProfileDialog";
+import { fetchUserProfile } from "../../api/profileApi";
+import { useState } from "react";
+import { delay } from "../../../utils/utils";
 
 export function ChatMessages() {
     const { messages } = useChat();
     const { user } = useAppState();
+    const [profileDialogOpen, setProfileDialogOpen] = useState(false);
+    const [selectedUserProfile, setSelectedUserProfile] = useState<UserProfile | null>(null);
+    const [isLoadingProfile, setIsLoadingProfile] = useState(false);
 
-    const handleProfileClick = (username: string) => {
-        // TODO: Show user profile dialog
-        console.log("Show profile for:", username);
+    const handleProfileClick = async (username: string) => {
+        if (!user.authToken) return;
+        
+        setIsLoadingProfile(true);
+        try {
+            const profile = await fetchUserProfile(user.authToken, username);
+            if (profile) {
+                setSelectedUserProfile(profile);
+                setProfileDialogOpen(true);
+            }
+        } catch (error) {
+            console.error("Failed to fetch user profile:", error);
+        } finally {
+            setIsLoadingProfile(false);
+        }
     };
 
     const handleContextMenu = (e: React.MouseEvent, message: MessageType) => {
@@ -19,16 +39,31 @@ export function ChatMessages() {
     };
 
     return (
-        <div className="chat-messages" id="chat-messages">
-            {messages.map((message) => (
-                <Message
-                    key={message.id}
-                    message={message}
-                    isAuthor={message.username === user.currentUser?.username}
-                    onProfileClick={handleProfileClick}
-                    onContextMenu={handleContextMenu}
-                />
-            ))}
-        </div>
+        <>
+            <div className="chat-messages" id="chat-messages">
+                {messages.map((message) => (
+                    <Message
+                        key={message.id}
+                        message={message}
+                        isAuthor={message.username === user.currentUser?.username}
+                        onProfileClick={handleProfileClick}
+                        onContextMenu={handleContextMenu}
+                        isLoadingProfile={isLoadingProfile}
+                    />
+                ))}
+            </div>
+            
+            <UserProfileDialog
+                isOpen={profileDialogOpen}
+                onOpenChange={async (value) => {
+                    setProfileDialogOpen(value);
+                    if (!value) {
+                        await delay(1000);
+                        setSelectedUserProfile(null);
+                    }
+                }}
+                userProfile={selectedUserProfile}
+            />
+        </>
     );
 }
diff --git a/frontend/src/ui/components/chat/Message.tsx b/frontend/src/ui/components/chat/Message.tsx
index 8e44817..6817f2a 100644
--- a/frontend/src/ui/components/chat/Message.tsx
+++ b/frontend/src/ui/components/chat/Message.tsx
@@ -7,9 +7,10 @@ interface MessageProps {
     isAuthor: boolean;
     onProfileClick: (username: string) => void;
     onContextMenu: (e: React.MouseEvent, message: MessageType) => void;
+    isLoadingProfile?: boolean;
 }
 
-export function Message({ message, isAuthor, onProfileClick, onContextMenu }: MessageProps) {
+export function Message({ message, isAuthor, onProfileClick, onContextMenu, isLoadingProfile = false }: MessageProps) {
     return (
         <div 
             className={`message ${isAuthor ? "sent" : "received"}`}
@@ -23,8 +24,9 @@ export function Message({ message, isAuthor, onProfileClick, onContextMenu }: Me
                         <img
                             src={message.profile_picture || defaultAvatar}
                             alt={message.username}
-                            onClick={() => onProfileClick(message.username)}
-                            style={{ cursor: "pointer" }}
+                            onClick={() => !isLoadingProfile && onProfileClick(message.username)}
+                            style={{ cursor: isLoadingProfile ? "default" : "pointer" }}
+                            className={isLoadingProfile ? "loading" : ""}
                             onError={(e) => {
                                 const target = e.target as HTMLImageElement;
                                 target.src = defaultAvatar;
@@ -35,9 +37,9 @@ export function Message({ message, isAuthor, onProfileClick, onContextMenu }: Me
 
                 {!isAuthor && (
                     <div 
-                        className="message-username" 
-                        onClick={() => onProfileClick(message.username)} 
-                        style={{ cursor: "pointer" }}> {/* TODO extract to SCSS */}
+                        className={`message-username ${isLoadingProfile ? "loading" : ""}`}
+                        onClick={() => !isLoadingProfile && onProfileClick(message.username)} 
+                        style={{ cursor: isLoadingProfile ? "default" : "pointer" }}> {/* TODO extract to SCSS */}
                         {message.username}
                     </div>
                 )}
diff --git a/frontend/src/ui/components/chat/UserProfileDialog.tsx b/frontend/src/ui/components/chat/UserProfileDialog.tsx
index 70291ba..b3cbdc9 100644
--- a/frontend/src/ui/components/chat/UserProfileDialog.tsx
+++ b/frontend/src/ui/components/chat/UserProfileDialog.tsx
@@ -1,40 +1,71 @@
 import type { DialogProps } from "../../../core/types";
+import type { UserProfile } from "../../../core/types";
 import { MaterialDialog } from "../Dialog";
+import { formatTime } from "../../../utils/utils";
+import defaultAvatar from "../../../resources/images/default-avatar.png";
 
-export function UserProfileDialog({ isOpen, onOpenChange }: DialogProps) {
-    return (
-        <MaterialDialog open={isOpen} onOpenChange={onOpenChange} close-on-overlay-click close-on-esc>
-            <div className="content">
-                <div className="profile-picture-section">
-                    <img className="profile-picture" alt="Profile Picture" />
+interface UserProfileDialogProps extends DialogProps {
+    userProfile: UserProfile | null;
+}
+
+export function UserProfileDialog({ isOpen, onOpenChange, userProfile }: UserProfileDialogProps) {
+    const content = userProfile ? (
+        <div className="content">
+            <div className="profile-picture-section">
+                <img 
+                    className="profile-picture" 
+                    alt="Profile Picture" 
+                    src={userProfile.profile_picture || defaultAvatar}
+                    onError={(e) => {
+                        const target = e.target as HTMLImageElement;
+                        target.src = defaultAvatar;
+                    }}
+                />
+            </div>
+            <div className="profile-info">
+                <div className="username-section">
+                    <h4 className="username">{userProfile.username}</h4>
+                    <div className={`online-status ${userProfile.online ? "online" : "offline"}`}>
+                        {userProfile.online ? (
+                            <>
+                                <span className="online-indicator"></span> Online
+                            </>
+                        ) : (
+                            <>
+                                <span className="offline-indicator"></span> Last seen {formatTime(userProfile.last_seen)}
+                            </>
+                        )}
+                    </div>
                 </div>
-                <div className="profile-info">
-                    <div className="username-section">
-                        <h4 className="username"></h4>
-                        <div className="online-status"></div>
+                <div className="bio-section">
+                    <label>Bio:</label>
+                    <div className="bio-display">
+                        {userProfile.bio || "No bio available."}
                     </div>
-                    <div className="bio-section">
-                        <label>Bio:</label>
-                        <div className="bio-display"></div>
+                </div>
+                <div className="profile-stats">
+                    <div className="stat">
+                        <span className="stat-label">Member since:</span>
+                        <span className="stat-value member-since">{formatTime(userProfile.created_at)}</span>
                     </div>
-                    <div className="profile-stats">
-                        <div className="stat">
-                            <span className="stat-label">Member since:</span>
-                            <span className="stat-value member-since"></span>
-                        </div>
-                        <div className="stat">
-                            <span className="stat-label">Last seen:</span>
-                            <span className="stat-value last-seen"></span>
-                        </div>
-                    </div>
-                    <div className="profile-actions">
-                        <mdui-button id="dm-button" variant="filled">
-                            <mdui-icon slot="icon" name="chat--filled"></mdui-icon>
-                            Send Message
-                        </mdui-button>
+                    <div className="stat">
+                        <span className="stat-label">Last seen:</span>
+                        <span className="stat-value last-seen">{formatTime(userProfile.last_seen)}</span>
                     </div>
                 </div>
+                <div className="profile-actions">
+                    <mdui-button id="dm-button" variant="filled">
+                        <mdui-icon slot="icon" name="chat--filled"></mdui-icon>
+                        Send Message
+                    </mdui-button>
+                </div>
             </div>
+        </div>
+    ) : null
+
+    return (
+        <MaterialDialog open={isOpen} onOpenChange={onOpenChange} close-on-overlay-click close-on-esc id="user-profile-dialog">
+            {content}
         </MaterialDialog>
     );
 }