diff --git a/CHANGELOG.md b/CHANGELOG.md
index 66837034ae..143a48ce48 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@
 - Enhance: チャットの日本語名称がダイレクトメッセージに戻るとともに、ベータ版機能ではなくなりました
 - Enhance: 画像編集にマスクエフェクト(塗りつぶし、ぼかし)を追加
 - Enhance: ウォーターマークにアカウントのQRコードを追加できるように
+- Enhance: テーマをドラッグ&ドロップできるように
 - Enhance: 絵文字ピッカーのサイズをより大きくできるように
 - Enhance: 時刻計算のための基準値を一か所で管理するようにし、パフォーマンスを向上
 - Fix: iOSで、デバイスがダークモードだと初回読み込み時にエラーになる問題を修正
diff --git a/packages/frontend/src/drag-and-drop.ts b/packages/frontend/src/drag-and-drop.ts
index 3c6f22f24b..670912241e 100644
--- a/packages/frontend/src/drag-and-drop.ts
+++ b/packages/frontend/src/drag-and-drop.ts
@@ -23,6 +23,15 @@ export function setDragData<T extends keyof DragDataMap>(
 	event.dataTransfer.setData(`misskey/${type}`.toLowerCase(), JSON.stringify(data));
 }
 
+export function setPlainDragData(
+	event: DragEvent,
+	data: string,
+) {
+	if (event.dataTransfer == null) return;
+
+	event.dataTransfer.setData('text/plain', data);
+}
+
 export function getDragData<T extends keyof DragDataMap>(
 	event: DragEvent,
 	type: T,
@@ -35,6 +44,17 @@ export function getDragData<T extends keyof DragDataMap>(
 	return JSON.parse(data);
 }
 
+export function getPlainDragData(
+	event: DragEvent,
+): string | null {
+	if (event.dataTransfer == null) return null;
+
+	const data = event.dataTransfer.getData('text/plain');
+	if (data == null || data === '') return null;
+
+	return data;
+}
+
 export function checkDragDataType(
 	event: DragEvent,
 	types: (keyof DragDataMap)[],
diff --git a/packages/frontend/src/pages/settings/theme.vue b/packages/frontend/src/pages/settings/theme.vue
index beae1224e4..0129aebe94 100644
--- a/packages/frontend/src/pages/settings/theme.vue
+++ b/packages/frontend/src/pages/settings/theme.vue
@@ -5,7 +5,11 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <template>
 <SearchMarker path="/settings/theme" :label="i18n.ts.theme" :keywords="['theme']" icon="ti ti-palette">
-	<div class="_gaps_m">
+	<div
+		class="_gaps_m"
+		@dragover.prevent.stop="onDragover"
+		@drop.prevent.stop="onDrop"
+	>
 		<div v-adaptive-border class="rfqxtzch _panel">
 			<div class="toggle">
 				<div class="toggleWrapper">
@@ -58,7 +62,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 											:class="$style.themeRadio"
 											:value="instanceLightTheme.id"
 										/>
-										<label :for="`themeRadio_${instanceLightTheme.id}`" :class="$style.themeItemRoot" class="_button" @contextmenu.prevent.stop="onThemeContextmenu(instanceLightTheme, $event)">
+										<label :for="`themeRadio_${instanceLightTheme.id}`" :class="$style.themeItemRoot" class="_button" draggable="true" @dragstart="onThemeDragstart($event, instanceLightTheme)" @contextmenu.prevent.stop="onThemeContextmenu(instanceLightTheme, $event)">
 											<MkThemePreview :theme="instanceLightTheme" :class="$style.themeItemPreview"/>
 											<div :class="$style.themeItemCaption">{{ instanceLightTheme.name }}</div>
 										</label>
@@ -78,7 +82,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 											:class="$style.themeRadio"
 											:value="theme.id"
 										/>
-										<label :for="`themeRadio_${theme.id}`" :class="$style.themeItemRoot" class="_button" @contextmenu.prevent.stop="onThemeContextmenu(theme, $event)">
+										<label :for="`themeRadio_${theme.id}`" :class="$style.themeItemRoot" class="_button" draggable="true" @dragstart="onThemeDragstart($event, theme)" @contextmenu.prevent.stop="onThemeContextmenu(theme, $event)">
 											<MkThemePreview :theme="theme" :class="$style.themeItemPreview"/>
 											<div :class="$style.themeItemCaption">{{ theme.name }}</div>
 										</label>
@@ -98,7 +102,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 											:class="$style.themeRadio"
 											:value="theme.id"
 										/>
-										<label :for="`themeRadio_${theme.id}`" :class="$style.themeItemRoot" class="_button" @contextmenu.prevent.stop="onThemeContextmenu(theme, $event)">
+										<label :for="`themeRadio_${theme.id}`" :class="$style.themeItemRoot" class="_button" draggable="true" @dragstart="onThemeDragstart($event, theme)" @contextmenu.prevent.stop="onThemeContextmenu(theme, $event)">
 											<MkThemePreview :theme="theme" :class="$style.themeItemPreview"/>
 											<div :class="$style.themeItemCaption">{{ theme.name }}</div>
 										</label>
@@ -129,7 +133,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 											:class="$style.themeRadio"
 											:value="instanceDarkTheme.id"
 										/>
-										<label :for="`themeRadio_${instanceDarkTheme.id}`" :class="$style.themeItemRoot" class="_button" @contextmenu.prevent.stop="onThemeContextmenu(instanceDarkTheme, $event)">
+										<label :for="`themeRadio_${instanceDarkTheme.id}`" :class="$style.themeItemRoot" class="_button" draggable="true" @dragstart="onThemeDragstart($event, instanceDarkTheme)" @contextmenu.prevent.stop="onThemeContextmenu(instanceDarkTheme, $event)">
 											<MkThemePreview :theme="instanceDarkTheme" :class="$style.themeItemPreview"/>
 											<div :class="$style.themeItemCaption">{{ instanceDarkTheme.name }}</div>
 										</label>
@@ -149,7 +153,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 											:class="$style.themeRadio"
 											:value="theme.id"
 										/>
-										<label :for="`themeRadio_${theme.id}`" :class="$style.themeItemRoot" class="_button" @contextmenu.prevent.stop="onThemeContextmenu(theme, $event)">
+										<label :for="`themeRadio_${theme.id}`" :class="$style.themeItemRoot" class="_button" draggable="true" @dragstart="onThemeDragstart($event, theme)" @contextmenu.prevent.stop="onThemeContextmenu(theme, $event)">
 											<MkThemePreview :theme="theme" :class="$style.themeItemPreview"/>
 											<div :class="$style.themeItemCaption">{{ theme.name }}</div>
 										</label>
@@ -169,7 +173,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 											:class="$style.themeRadio"
 											:value="theme.id"
 										/>
-										<label :for="`themeRadio_${theme.id}`" :class="$style.themeItemRoot" class="_button" @contextmenu.prevent.stop="onThemeContextmenu(theme, $event)">
+										<label :for="`themeRadio_${theme.id}`" :class="$style.themeItemRoot" class="_button" draggable="true" @dragstart="onThemeDragstart($event, theme)" @contextmenu.prevent.stop="onThemeContextmenu(theme, $event)">
 											<MkThemePreview :theme="theme" :class="$style.themeItemPreview"/>
 											<div :class="$style.themeItemCaption">{{ theme.name }}</div>
 										</label>
@@ -214,7 +218,7 @@ import FormLink from '@/components/form/link.vue';
 import MkFolder from '@/components/MkFolder.vue';
 import MkThemePreview from '@/components/MkThemePreview.vue';
 import MkInfo from '@/components/MkInfo.vue';
-import { getBuiltinThemesRef, getThemesRef, removeTheme } from '@/theme.js';
+import { getBuiltinThemesRef, getThemesRef, installTheme, parseThemeCode, removeTheme } from '@/theme.js';
 import { isDeviceDarkmode } from '@/utility/is-device-darkmode.js';
 import { store } from '@/store.js';
 import { i18n } from '@/i18n.js';
@@ -223,6 +227,7 @@ import { uniqueBy } from '@/utility/array.js';
 import { definePage } from '@/page.js';
 import { prefer } from '@/preferences.js';
 import { copyToClipboard } from '@/utility/copy-to-clipboard.js';
+import { checkDragDataType, getDragData, getPlainDragData, setDragData, setPlainDragData } from '@/drag-and-drop.js';
 
 const installedThemes = getThemesRef();
 const builtinThemes = getBuiltinThemesRef();
@@ -321,6 +326,38 @@ function onThemeContextmenu(theme: Theme, ev: MouseEvent) {
 	}], ev);
 }
 
+function onThemeDragstart(ev: DragEvent, theme: Theme) {
+	if (!ev.dataTransfer) return;
+
+	ev.dataTransfer.effectAllowed = 'copy';
+	setPlainDragData(ev, JSON5.stringify(theme, null, '\t'));
+}
+
+function onDragover(ev: DragEvent) {
+	if (!ev.dataTransfer) return;
+
+	if (ev.dataTransfer.types[0] === 'text/plain') {
+		ev.dataTransfer.dropEffect = 'copy';
+	} else {
+		ev.dataTransfer.dropEffect = 'none';
+	}
+
+	return false;
+}
+
+async function onDrop(ev: DragEvent) {
+	if (!ev.dataTransfer) return;
+
+	const code = getPlainDragData(ev);
+	if (code != null) {
+		try {
+			await installTheme(code);
+		} catch (err) {
+			// nop
+		}
+	}
+}
+
 const headerActions = computed(() => []);
 
 const headerTabs = computed(() => []);