diff --git a/CHANGELOG.md b/CHANGELOG.md
index 99ef3a36ab..694f330120 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,7 @@
 ### Client
 - Feat: 今日誕生日のフォロー中のユーザーを一覧表示できるウィジェットを追加
 - Feat: データセーバーでコードハイライトの読み込みを削減できるように
+- Enhance: 投稿フォームの絵文字ピッカーをリアクション時に使用するものと同じのを使用するように #12336
 - Enhance: 絵文字のオートコンプリート機能強化 #12364
 - Enhance: ユーザーのRawデータを表示するページが復活
 - Enhance: リアクション選択時に音を鳴らせるように
diff --git a/packages/frontend/src/boot/main-boot.ts b/packages/frontend/src/boot/main-boot.ts
index 71236e4c53..88e2f83895 100644
--- a/packages/frontend/src/boot/main-boot.ts
+++ b/packages/frontend/src/boot/main-boot.ts
@@ -19,6 +19,7 @@ import { claimAchievement, claimedAchievements } from '@/scripts/achievements.js
 import { mainRouter } from '@/router.js';
 import { initializeSw } from '@/scripts/initialize-sw.js';
 import { deckStore } from '@/ui/deck/deck-store.js';
+import { emojiPicker } from '@/scripts/emoji-picker.js';
 
 export async function mainBoot() {
 	const { isClientUpdated } = await common(() => createApp(
@@ -30,6 +31,7 @@ export async function mainBoot() {
 	));
 
 	reactionPicker.init();
+	emojiPicker.init();
 
 	if (isClientUpdated && $i) {
 		popup(defineAsyncComponent(() => import('@/components/MkUpdated.vue')), {}, {}, 'closed');
diff --git a/packages/frontend/src/components/MkEmojiPicker.vue b/packages/frontend/src/components/MkEmojiPicker.vue
index ecff2b5ace..b5e5a0260c 100644
--- a/packages/frontend/src/components/MkEmojiPicker.vue
+++ b/packages/frontend/src/components/MkEmojiPicker.vue
@@ -36,7 +36,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 		</section>
 
 		<div v-if="tab === 'index'" class="group index">
-			<section v-if="showPinned">
+			<section v-if="showPinned && pinned.length > 0">
 				<div class="body">
 					<button
 						v-for="emoji in pinned"
@@ -137,7 +137,7 @@ const searchEl = shallowRef<HTMLInputElement>();
 const emojisEl = shallowRef<HTMLDivElement>();
 
 const {
-	reactions: pinned,
+	reactions: pinnedReactions,
 	reactionPickerSize,
 	reactionPickerWidth,
 	reactionPickerHeight,
@@ -145,6 +145,7 @@ const {
 	recentlyUsedEmojis,
 } = defaultStore.reactiveState;
 
+const pinned = computed(() => props.asReactionPicker ? pinnedReactions.value : []); // TODO: 非リアクションの絵文字ピッカー用のpinned絵文字を設定可能にする？
 const size = computed(() => props.asReactionPicker ? reactionPickerSize.value : 1);
 const width = computed(() => props.asReactionPicker ? reactionPickerWidth.value : 3);
 const height = computed(() => props.asReactionPicker ? reactionPickerHeight.value : 2);
diff --git a/packages/frontend/src/components/MkEmojiPickerDialog.vue b/packages/frontend/src/components/MkEmojiPickerDialog.vue
index 9d3132c540..05b137e335 100644
--- a/packages/frontend/src/components/MkEmojiPickerDialog.vue
+++ b/packages/frontend/src/components/MkEmojiPickerDialog.vue
@@ -31,20 +31,21 @@ SPDX-License-Identifier: AGPL-3.0-only
 </template>
 
 <script lang="ts" setup>
-import { shallowRef } from 'vue';
 import MkModal from '@/components/MkModal.vue';
 import MkEmojiPicker from '@/components/MkEmojiPicker.vue';
 import { defaultStore } from '@/store.js';
 
-withDefaults(defineProps<{
+const props = withDefaults(defineProps<{
 	manualShowing?: boolean | null;
 	src?: HTMLElement;
 	showPinned?: boolean;
 	asReactionPicker?: boolean;
+  choseAndClose?: boolean;
 }>(), {
 	manualShowing: null,
 	showPinned: true,
 	asReactionPicker: false,
+	choseAndClose: true,
 });
 
 const emit = defineEmits<{
@@ -53,21 +54,23 @@ const emit = defineEmits<{
 	(ev: 'closed'): void;
 }>();
 
-const modal = shallowRef<InstanceType<typeof MkModal>>();
-const picker = shallowRef<InstanceType<typeof MkEmojiPicker>>();
+const modal = $shallowRef<InstanceType<typeof MkModal>>();
+const picker = $shallowRef<InstanceType<typeof MkEmojiPicker>>();
 
 function chosen(emoji: any) {
 	emit('done', emoji);
-	modal.value?.close();
+	if (props.choseAndClose) {
+		modal?.close();
+	}
 }
 
 function opening() {
-	picker.value?.reset();
-	picker.value?.focus();
+	picker?.reset();
+	picker?.focus();
 
 	// 何故かちょっと待たないとフォーカスされない
 	setTimeout(() => {
-		picker.value?.focus();
+		picker?.focus();
 	}, 10);
 }
 </script>
diff --git a/packages/frontend/src/components/MkPostForm.vue b/packages/frontend/src/components/MkPostForm.vue
index 3244f743ac..0445536ae5 100644
--- a/packages/frontend/src/components/MkPostForm.vue
+++ b/packages/frontend/src/components/MkPostForm.vue
@@ -124,6 +124,7 @@ import { deepClone } from '@/scripts/clone.js';
 import MkRippleEffect from '@/components/MkRippleEffect.vue';
 import { miLocalStorage } from '@/local-storage.js';
 import { claimAchievement } from '@/scripts/achievements.js';
+import { emojiPicker } from '@/scripts/emoji-picker.js';
 
 const modal = inject('modal');
 
@@ -845,7 +846,15 @@ function insertMention() {
 }
 
 async function insertEmoji(ev: MouseEvent) {
-	os.openEmojiPicker(ev.currentTarget ?? ev.target, {}, textareaEl);
+	emojiPicker.show(
+		ev.currentTarget ?? ev.target,
+		emoji => {
+			insertTextAtCursor(textareaEl, emoji);
+		},
+		() => {
+			focus();
+		},
+	);
 }
 
 function showActions(ev) {
diff --git a/packages/frontend/src/scripts/emoji-picker.ts b/packages/frontend/src/scripts/emoji-picker.ts
new file mode 100644
index 0000000000..d6d6bf1245
--- /dev/null
+++ b/packages/frontend/src/scripts/emoji-picker.ts
@@ -0,0 +1,57 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and other misskey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { defineAsyncComponent, Ref, ref } from 'vue';
+import { popup } from '@/os.js';
+
+/**
+ * 絵文字ピッカーを表示する。
+ * 類似の機能として{@link ReactionPicker}が存在しているが、この機能とは動きが異なる。
+ * 投稿フォームなどで絵文字を選択する時など、絵文字ピックアップ後でもダイアログが消えずに残り、
+ * 一度表示したダイアログを連続で使用できることが望ましいシーンでの利用が想定される。
+ */
+class EmojiPicker {
+	private src: Ref<HTMLElement | null> = ref(null);
+	private manualShowing = ref(false);
+	private onChosen?: (emoji: string) => void;
+	private onClosed?: () => void;
+
+	constructor() {
+		// nop
+	}
+
+	public async init() {
+		await popup(defineAsyncComponent(() => import('@/components/MkEmojiPickerDialog.vue')), {
+			src: this.src,
+			asReactionPicker: false,
+			manualShowing: this.manualShowing,
+			choseAndClose: false,
+		}, {
+			done: emoji => {
+				if (this.onChosen) this.onChosen(emoji);
+			},
+			close: () => {
+				this.manualShowing.value = false;
+			},
+			closed: () => {
+				this.src.value = null;
+				if (this.onClosed) this.onClosed();
+			},
+		});
+	}
+
+	public show(
+		src: HTMLElement,
+		onChosen: EmojiPicker['onChosen'],
+		onClosed: EmojiPicker['onClosed'],
+	) {
+		this.src.value = src;
+		this.manualShowing.value = true;
+		this.onChosen = onChosen;
+		this.onClosed = onClosed;
+	}
+}
+
+export const emojiPicker = new EmojiPicker();