diff --git a/app/Http/Controllers/PortalController.php b/app/Http/Controllers/PortalController.php
index cf3980d..7322f9b 100644
--- a/app/Http/Controllers/PortalController.php
+++ b/app/Http/Controllers/PortalController.php
@@ -99,6 +99,7 @@ class PortalController extends Controller
             'id' => $thread->id,
             'title' => $thread->title,
             'body' => $thread->body,
+            'solved' => (bool) $thread->solved,
             'forum' => "/api/forums/{$thread->forum_id}",
             'user_id' => $thread->user_id,
             'posts_count' => ($thread->posts_count ?? 0) + 1,
diff --git a/app/Http/Controllers/ThreadController.php b/app/Http/Controllers/ThreadController.php
index 21c4224..f82488a 100644
--- a/app/Http/Controllers/ThreadController.php
+++ b/app/Http/Controllers/ThreadController.php
@@ -97,6 +97,36 @@ class ThreadController extends Controller
         return response()->json(null, 204);
     }
 
+    public function updateSolved(Request $request, Thread $thread): JsonResponse
+    {
+        $user = $request->user();
+        if (!$user) {
+            return response()->json(['message' => 'Unauthorized.'], 401);
+        }
+
+        $isAdmin = $user->roles()->where('name', 'ROLE_ADMIN')->exists();
+        if (!$isAdmin && $thread->user_id !== $user->id) {
+            return response()->json(['message' => 'Not authorized to update solved status.'], 403);
+        }
+
+        $data = $request->validate([
+            'solved' => ['required', 'boolean'],
+        ]);
+
+        $thread->solved = $data['solved'];
+        $thread->save();
+        $thread->refresh();
+        $thread->loadMissing([
+            'user' => fn ($query) => $query
+                ->withCount(['posts', 'threads', 'thanksGiven', 'thanksReceived'])
+                ->with(['rank', 'roles']),
+            'latestPost.user.rank',
+            'latestPost.user.roles',
+        ])->loadCount('posts');
+
+        return response()->json($this->serializeThread($thread));
+    }
+
     private function parseIriId(?string $value): ?int
     {
         if (!$value) {
@@ -120,6 +150,7 @@ class ThreadController extends Controller
             'id' => $thread->id,
             'title' => $thread->title,
             'body' => $thread->body,
+            'solved' => (bool) $thread->solved,
             'forum' => "/api/forums/{$thread->forum_id}",
             'user_id' => $thread->user_id,
             'posts_count' => ($thread->posts_count ?? 0) + 1,
diff --git a/app/Models/Thread.php b/app/Models/Thread.php
index 2c78cea..755c8e9 100644
--- a/app/Models/Thread.php
+++ b/app/Models/Thread.php
@@ -14,6 +14,7 @@ use Illuminate\Database\Eloquent\SoftDeletes;
  * @property int|null $user_id
  * @property string $title
  * @property string $body
+ * @property bool $solved
  * @property \Illuminate\Support\Carbon|null $created_at
  * @property \Illuminate\Support\Carbon|null $updated_at
  * @property-read \App\Models\Forum $forum
@@ -41,6 +42,11 @@ class Thread extends Model
         'user_id',
         'title',
         'body',
+        'solved',
+    ];
+
+    protected $casts = [
+        'solved' => 'bool',
     ];
 
     public function forum(): BelongsTo
diff --git a/database/migrations/2026_01_24_120000_add_solved_to_threads_table.php b/database/migrations/2026_01_24_120000_add_solved_to_threads_table.php
new file mode 100644
index 0000000..655f60d
--- /dev/null
+++ b/database/migrations/2026_01_24_120000_add_solved_to_threads_table.php
@@ -0,0 +1,28 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('threads', function (Blueprint $table) {
+            $table->boolean('solved')->default(false)->after('body');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('threads', function (Blueprint $table) {
+            $table->dropColumn('solved');
+        });
+    }
+};
diff --git a/resources/js/api/client.js b/resources/js/api/client.js
index 8e84cbe..b63901a 100644
--- a/resources/js/api/client.js
+++ b/resources/js/api/client.js
@@ -246,6 +246,16 @@ export async function getThread(id) {
     return apiFetch(`/threads/${id}`)
 }
 
+export async function updateThreadSolved(threadId, solved) {
+    return apiFetch(`/threads/${threadId}/solved`, {
+        method: 'PATCH',
+        headers: {
+            'Content-Type': 'application/merge-patch+json',
+        },
+        body: JSON.stringify({ solved }),
+    })
+}
+
 export async function listPostsByThread(threadId) {
     return getCollection(`/posts?thread=/api/threads/${threadId}`)
 }
diff --git a/resources/js/components/PortalTopicRow.jsx b/resources/js/components/PortalTopicRow.jsx
index 563b9c8..c1394e3 100644
--- a/resources/js/components/PortalTopicRow.jsx
+++ b/resources/js/components/PortalTopicRow.jsx
@@ -39,6 +39,9 @@ export default function PortalTopicRow({ thread, forumName, forumId, showForum =
                 <div>
                     <Link to={`/thread/${thread.id}`} className="bb-portal-topic-title">
                         {thread.title}
+                        {thread.solved && (
+                            <span className="bb-thread-solved-badge">{t('thread.solved')}</span>
+                        )}
                     </Link>
                     <div className="bb-portal-topic-meta">
                         <div className="bb-portal-topic-meta-line">
diff --git a/resources/js/index.css b/resources/js/index.css
index 299d88b..4946e58 100644
--- a/resources/js/index.css
+++ b/resources/js/index.css
@@ -105,6 +105,40 @@ a {
   margin: 0;
   font-size: 1.6rem;
   color: var(--bb-accent, #f29b3f);
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  flex-wrap: wrap;
+}
+
+.bb-thread-solved-badge {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.25rem;
+  padding: 0.18rem 0.5rem;
+  border-radius: 999px;
+  background: var(--bb-accent, #f29b3f);
+  color: #0b0f17;
+  font-size: 0.75rem;
+  font-weight: 700;
+  letter-spacing: 0.04em;
+  text-transform: uppercase;
+  margin-left: 0.45rem;
+}
+
+.bb-thread-solved-toggle {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.4rem;
+  color: var(--bb-accent, #f29b3f);
+  border-color: var(--bb-accent, #f29b3f);
+}
+
+.bb-thread-solved-toggle:hover,
+.bb-thread-solved-toggle:focus {
+  background: var(--bb-accent, #f29b3f);
+  border-color: var(--bb-accent, #f29b3f);
+  color: #0b0f17;
 }
 
 .bb-thread-meta {
diff --git a/resources/js/pages/ThreadView.jsx b/resources/js/pages/ThreadView.jsx
index f437f5d..fb42db8 100644
--- a/resources/js/pages/ThreadView.jsx
+++ b/resources/js/pages/ThreadView.jsx
@@ -1,19 +1,20 @@
 import { useEffect, useMemo, useRef, useState } from 'react'
 import { Button, Container, Form } from 'react-bootstrap'
 import { useParams } from 'react-router-dom'
-import { createPost, getThread, listPostsByThread } from '../api/client'
+import { createPost, getThread, listPostsByThread, updateThreadSolved } from '../api/client'
 import { useAuth } from '../context/AuthContext'
 import { useTranslation } from 'react-i18next'
 
 export default function ThreadView() {
     const { id } = useParams()
-    const { token, userId } = useAuth()
+    const { token, userId, isAdmin } = useAuth()
     const [thread, setThread] = useState(null)
     const [posts, setPosts] = useState([])
     const [error, setError] = useState('')
     const [loading, setLoading] = useState(true)
     const [body, setBody] = useState('')
     const [saving, setSaving] = useState(false)
+    const [solving, setSolving] = useState(false)
     const { t } = useTranslation()
     const replyRef = useRef(null)
 
@@ -93,6 +94,24 @@ export default function ThreadView() {
         replyRef.current?.scrollIntoView({ behavior: 'smooth', block: 'start' })
     }
 
+    const canToggleSolved = token
+        && thread
+        && (Number(thread.user_id) === Number(userId) || isAdmin)
+
+    const handleToggleSolved = async () => {
+        if (!thread || solving) return
+        setSolving(true)
+        setError('')
+        try {
+            const updated = await updateThreadSolved(thread.id, !thread.solved)
+            setThread(updated)
+        } catch (err) {
+            setError(err.message)
+        } finally {
+            setSolving(false)
+        }
+    }
+
     const totalPosts = allPosts.length
 
     return (
@@ -102,7 +121,12 @@ export default function ThreadView() {
             {thread && (
                 <div className="bb-thread">
                     <div className="bb-thread-titlebar">
-                        <h1 className="bb-thread-title">{thread.title}</h1>
+                        <h1 className="bb-thread-title">
+                            {thread.title}
+                            {thread.solved && (
+                                <span className="bb-thread-solved-badge">{t('thread.solved')}</span>
+                            )}
+                        </h1>
                         <div className="bb-thread-meta">
                             <span>{t('thread.by')}</span>
                             <span className="bb-thread-author">
@@ -120,6 +144,20 @@ export default function ThreadView() {
                                 <i className="bi bi-reply-fill" aria-hidden="true" />
                                 <span>{t('form.post_reply')}</span>
                             </Button>
+                            {canToggleSolved && (
+                                <Button
+                                    variant="outline-secondary"
+                                    className="bb-thread-solved-toggle"
+                                    onClick={handleToggleSolved}
+                                    disabled={solving}
+                                >
+                                    <i
+                                        className={`bi ${thread.solved ? 'bi-check-circle-fill' : 'bi-check-circle'}`}
+                                        aria-hidden="true"
+                                    />
+                                    <span>{thread.solved ? t('thread.mark_unsolved') : t('thread.mark_solved')}</span>
+                                </Button>
+                            )}
                             <button type="button" className="bb-thread-icon-button" aria-label={t('thread.reply')}>
                                 <i className="bi bi-arrow-counterclockwise" aria-hidden="true" />
                             </button>
diff --git a/resources/lang/de.json b/resources/lang/de.json
index b9a4f20..73d0c8a 100644
--- a/resources/lang/de.json
+++ b/resources/lang/de.json
@@ -227,6 +227,9 @@
   "thread.reply_prefix": "Aw:",
   "thread.registered": "Registriert",
   "thread.replies": "Antworten",
+  "thread.solved": "Gel\u00f6st",
+  "thread.mark_solved": "Als gel\u00f6st markieren",
+  "thread.mark_unsolved": "Als ungel\u00f6st markieren",
   "thread.views": "Zugriffe",
   "thread.last_post": "Letzter Beitrag",
   "thread.by": "von",
diff --git a/resources/lang/en.json b/resources/lang/en.json
index 7887255..9ae3537 100644
--- a/resources/lang/en.json
+++ b/resources/lang/en.json
@@ -227,6 +227,9 @@
   "thread.reply_prefix": "Re:",
   "thread.registered": "Registered",
   "thread.replies": "Replies",
+  "thread.solved": "Solved",
+  "thread.mark_solved": "Mark solved",
+  "thread.mark_unsolved": "Mark unsolved",
   "thread.views": "Views",
   "thread.last_post": "Last post",
   "thread.by": "by",
diff --git a/routes/api.php b/routes/api.php
index 21d976f..55e6f34 100644
--- a/routes/api.php
+++ b/routes/api.php
@@ -67,6 +67,7 @@ Route::delete('/forums/{forum}', [ForumController::class, 'destroy'])->middlewar
 Route::get('/threads', [ThreadController::class, 'index']);
 Route::get('/threads/{thread}', [ThreadController::class, 'show']);
 Route::post('/threads', [ThreadController::class, 'store'])->middleware('auth:sanctum');
+Route::patch('/threads/{thread}/solved', [ThreadController::class, 'updateSolved'])->middleware('auth:sanctum');
 Route::delete('/threads/{thread}', [ThreadController::class, 'destroy'])->middleware('auth:sanctum');
 
 Route::get('/posts', [PostController::class, 'index']);