diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8728ebf733..60bc28e077 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,7 @@
 - Fix: MkSignin.vueのcredentialRequestからReactivityを削除（ProxyがPasskey認証処理に渡ることを避けるため）
 - Fix: 「アニメーション画像を再生しない」がオンのときでもサーバーのバナー画像・背景画像がアニメーションしてしまう問題を修正  
   (Cherry-picked from https://activitypub.software/TransFem-org/Sharkey/-/merge_requests/574)
+- Fix: Twitchの埋め込みが開けない問題を修正
 
 ### Server
 - Feat: レートリミット制限に引っかかったときに`Retry-After`ヘッダーを返すように (#13949)
diff --git a/packages/frontend/src/components/MkUrlPreview.vue b/packages/frontend/src/components/MkUrlPreview.vue
index 8df5e0fe40..c868a22045 100644
--- a/packages/frontend/src/components/MkUrlPreview.vue
+++ b/packages/frontend/src/components/MkUrlPreview.vue
@@ -15,7 +15,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 			scrolling="no"
 			:allow="player.allow == null ? 'autoplay;encrypted-media;fullscreen' : player.allow.filter(x => ['autoplay', 'clipboard-write', 'fullscreen', 'encrypted-media', 'picture-in-picture', 'web-share'].includes(x)).join(';')"
 			:class="$style.playerIframe"
-			:src="player.url + (player.url.match(/\?/) ? '&autoplay=1&auto_play=1' : '?autoplay=1&auto_play=1')"
+			:src="transformPlayerUrl(player.url)"
 			:style="{ border: 0 }"
 		></iframe>
 		<span v-else>invalid url</span>
@@ -91,6 +91,7 @@ import * as os from '@/os.js';
 import { deviceKind } from '@/scripts/device-kind.js';
 import MkButton from '@/components/MkButton.vue';
 import { versatileLang } from '@/scripts/intl-const.js';
+import { transformPlayerUrl } from '@/scripts/player-url-transform.js';
 import { defaultStore } from '@/store.js';
 
 type SummalyResult = Awaited<ReturnType<typeof summaly>>;
diff --git a/packages/frontend/src/components/MkYouTubePlayer.vue b/packages/frontend/src/components/MkYouTubePlayer.vue
index 1fad222fc5..e3711b3463 100644
--- a/packages/frontend/src/components/MkYouTubePlayer.vue
+++ b/packages/frontend/src/components/MkYouTubePlayer.vue
@@ -13,7 +13,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 	<div class="poamfof">
 		<Transition :name="defaultStore.state.animation ? 'fade' : ''" mode="out-in">
 			<div v-if="player.url && (player.url.startsWith('http://') || player.url.startsWith('https://'))" class="player">
-				<iframe v-if="!fetching" :src="player.url + (player.url.match(/\?/) ? '&autoplay=1&auto_play=1' : '?autoplay=1&auto_play=1')" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen/>
+				<iframe v-if="!fetching" :src="transformPlayerUrl(player.url)" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
 			</div>
 			<span v-else>invalid url</span>
 		</Transition>
@@ -27,6 +27,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 import { ref } from 'vue';
 import MkWindow from '@/components/MkWindow.vue';
 import { versatileLang } from '@/scripts/intl-const.js';
+import { transformPlayerUrl } from '@/scripts/player-url-transform.js';
 import { defaultStore } from '@/store.js';
 
 const props = defineProps<{
diff --git a/packages/frontend/src/scripts/player-url-transform.ts b/packages/frontend/src/scripts/player-url-transform.ts
new file mode 100644
index 0000000000..53b2a9e441
--- /dev/null
+++ b/packages/frontend/src/scripts/player-url-transform.ts
@@ -0,0 +1,26 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { hostname } from '@/config.js';
+
+export function transformPlayerUrl(url: string): string {
+	const urlObj = new URL(url);
+	if (!['https:', 'http:'].includes(urlObj.protocol)) throw new Error('Invalid protocol');
+
+	const urlParams = new URLSearchParams(urlObj.search);
+
+	if (urlObj.hostname === 'player.twitch.tv') {
+		// TwitchはCSPの制約あり
+		// https://dev.twitch.tv/docs/embed/video-and-clips/
+		urlParams.set('parent', hostname);
+		urlParams.set('allowfullscreen', '');
+		urlParams.set('autoplay', 'true');
+	} else {
+		urlParams.set('autoplay', '1');
+		urlParams.set('auto_play', '1');
+	}
+	urlObj.search = urlParams.toString();
+
+	return urlObj.toString();
+}