diff --git a/.changeset/wise-months-taste.md b/.changeset/wise-months-taste.md
new file mode 100644
index 00000000000..d60d758db09
--- /dev/null
+++ b/.changeset/wise-months-taste.md
@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+Add support for custom emojis and a declarative "loading" state in `MarkdownEditor` suggestions
diff --git a/src/drafts/MarkdownEditor/MarkdownEditor.stories.tsx b/src/drafts/MarkdownEditor/MarkdownEditor.stories.tsx
index f140894d2c2..de951a2eac9 100644
--- a/src/drafts/MarkdownEditor/MarkdownEditor.stories.tsx
+++ b/src/drafts/MarkdownEditor/MarkdownEditor.stories.tsx
@@ -163,6 +163,7 @@ const emojis: Emoji[] = [
   {name: 'raised_hand', character: '✋'},
   {name: 'thumbsup', character: '👍'},
   {name: 'thumbsdown', character: '👎'},
+  {name: 'octocat', url: 'https://github.githubassets.com/images/icons/emoji/octocat.png'},
 ]
 
 const references: Reference[] = [
diff --git a/src/drafts/MarkdownEditor/MarkdownEditor.test.tsx b/src/drafts/MarkdownEditor/MarkdownEditor.test.tsx
index b946c373b6c..ce0b57c93c4 100644
--- a/src/drafts/MarkdownEditor/MarkdownEditor.test.tsx
+++ b/src/drafts/MarkdownEditor/MarkdownEditor.test.tsx
@@ -4,7 +4,7 @@ import userEvent from '@testing-library/user-event'
 import {UserEvent} from '@testing-library/user-event/dist/types/setup/setup'
 import React, {forwardRef, useRef, useState} from 'react'
 import {act} from 'react-dom/test-utils'
-import MarkdownEditor, {Emoji, MarkdownEditorHandle, MarkdownEditorProps, Mentionable, Reference, SavedReply} from '.'
+import MarkdownEditor, {MarkdownEditorHandle, MarkdownEditorProps, Mentionable, Reference, SavedReply} from '.'
 import ThemeProvider from '../../ThemeProvider'
 
 declare const REACT_VERSION_LATEST: boolean
@@ -866,12 +866,13 @@ describe('MarkdownEditor', () => {
   })
 
   describe('suggestions', () => {
-    const emojis: Emoji[] = [
+    const emojis = [
       {name: '+1', character: '👍'},
       {name: '-1', character: '👎'},
       {name: 'heart', character: '❤️'},
       {name: 'wave', character: '👋'},
       {name: 'raised_hands', character: '🙌'},
+      {name: 'octocat', url: 'https://github.githubassets.com/images/icons/emoji/octocat.png'},
     ]
 
     const mentionables: Mentionable[] = [
@@ -1076,6 +1077,17 @@ describe('MarkdownEditor', () => {
       expect(getAllSuggestions()[0]).toHaveTextContent('+1')
       expect(getAllSuggestions()[1]).toHaveTextContent('-1')
     })
+
+    it('inserts shortcode for custom emojis', async () => {
+      const {queryForSuggestionsList, getAllSuggestions, getInput, user} = await render(<EditorWithSuggestions />)
+
+      const input = getInput()
+      await user.type(input, `Mona Lisa :octo`)
+      await user.click(getAllSuggestions()[0])
+
+      expect(input.value).toBe(`Mona Lisa :octocat: `)
+      expect(queryForSuggestionsList()).not.toBeInTheDocument()
+    })
   })
 
   describe('saved replies', () => {
diff --git a/src/drafts/MarkdownEditor/suggestions/_useEmojiSuggestions.tsx b/src/drafts/MarkdownEditor/suggestions/_useEmojiSuggestions.tsx
index c9e78942680..ec3108f1387 100644
--- a/src/drafts/MarkdownEditor/suggestions/_useEmojiSuggestions.tsx
+++ b/src/drafts/MarkdownEditor/suggestions/_useEmojiSuggestions.tsx
@@ -3,24 +3,40 @@ import {suggestionsCalculator, UseSuggestionsHook} from '.'
 import {ActionList} from '../../../ActionList'
 import {Suggestion, Trigger} from '../../InlineAutocomplete'
 
-export type Emoji = {
+type BaseEmoji = {
   /** Name (shortcode) of the emoji. Do not include the wrapping `:` symbols. */
   name: string
+}
+
+type UnicodeEmoji = BaseEmoji & {
   /** Unicode representation of the emoji. */
   character: string
 }
 
+type CustomEmoji = BaseEmoji & {
+  /** URL to an image of the emoji. */
+  url: string
+}
+
+export type Emoji = UnicodeEmoji | CustomEmoji
+
 const trigger: Trigger = {
   triggerChar: ':',
   keepTriggerCharOnCommit: false,
 }
 
 const emojiToSugggestion = (emoji: Emoji): Suggestion => ({
-  value: emoji.character,
-  key: emoji.name, // emoji characters may not be unique - ie haircut and haircut_man both have the same emoji codepoint. But names are guarunteed to be unique.
+  value: 'character' in emoji ? emoji.character : `:${emoji.name}:`,
+  key: emoji.name, // emoji characters may not be unique - ie haircut and haircut_man both have the same emoji codepoint. But names are guaranteed to be unique.
   render: props => (
     <ActionList.Item {...props}>
-      <ActionList.LeadingVisual>{emoji.character}</ActionList.LeadingVisual>
+      <ActionList.LeadingVisual>
+        {'character' in emoji ? (
+          emoji.character
+        ) : (
+          <img src={emoji.url} alt={`${emoji.name} emoji`} height="16" width="16" />
+        )}
+      </ActionList.LeadingVisual>
       {emoji.name}
     </ActionList.Item>
   ),
diff --git a/src/drafts/MarkdownEditor/suggestions/index.ts b/src/drafts/MarkdownEditor/suggestions/index.ts
index 664180f3438..a00939c8ffd 100644
--- a/src/drafts/MarkdownEditor/suggestions/index.ts
+++ b/src/drafts/MarkdownEditor/suggestions/index.ts
@@ -2,11 +2,11 @@ import {Suggestion, Trigger} from '../../InlineAutocomplete'
 
 const MAX_SUGGESTIONS = 5
 
-export type SuggestionOptions<T> = T[] | (() => Promise<T[]>)
+export type SuggestionOptions<T> = T[] | (() => Promise<T[]>) | 'loading'
 
 export type UseSuggestionsHook<T> = (options: SuggestionOptions<T>) => {
   trigger: Trigger
-  calculateSuggestions: (query: string) => Promise<Suggestion[]>
+  calculateSuggestions: (query: string) => Promise<Suggestion[] | 'loading'>
 }
 
 export const suggestionsCalculator =
@@ -16,6 +16,8 @@ export const suggestionsCalculator =
     toSuggestion: (option: T) => Suggestion,
   ) =>
   async (query: string) => {
+    if (options === 'loading') return 'loading'
+
     const optionsArray = Array.isArray(options) ? options : await options()
 
     // If the query is empty, scores will be -INFINITY