diff --git a/packages/core/src/extensions/SuggestionMenu/SuggestionMenu.test.ts b/packages/core/src/extensions/SuggestionMenu/SuggestionMenu.test.ts
index f739fe9af4..2739a1d18b 100644
--- a/packages/core/src/extensions/SuggestionMenu/SuggestionMenu.test.ts
+++ b/packages/core/src/extensions/SuggestionMenu/SuggestionMenu.test.ts
@@ -188,4 +188,68 @@ describe("SuggestionMenu", () => {
 
     editor._tiptapEditor.destroy();
   });
+
+  it("should prefer a multi-character trigger over a shadowing single-character one", () => {
+    const editor = createEditor();
+    const sm = editor.getExtension(SuggestionMenu)!;
+
+    // Register the single-character trigger first so it would shadow the
+    // multi-character one in insertion order (mirrors the default emoji ":"
+    // menu registered before a custom "img:" menu).
+    sm.addSuggestionMenu({ triggerCharacter: ":" });
+    sm.addSuggestionMenu({ triggerCharacter: "img:" });
+
+    editor.replaceBlocks(editor.document, [
+      {
+        id: "paragraph-0",
+        type: "paragraph",
+        content: "img",
+      },
+    ]);
+
+    editor.setTextCursorPosition("paragraph-0", "end");
+
+    expect(getSuggestionPluginState(editor)).toBeUndefined();
+
+    // Typing the final ":" of "img:" should open the "img:" menu, not the ":"
+    // emoji menu.
+    const handled = simulateTextInput(editor, ":");
+
+    expect(handled).toBe(true);
+
+    const pluginState = getSuggestionPluginState(editor);
+    expect(pluginState).toBeDefined();
+    expect(pluginState.triggerCharacter).toBe("img:");
+
+    editor._tiptapEditor.destroy();
+  });
+
+  it("should match a multi-character trigger mid-line (not just at block start)", () => {
+    const editor = createEditor();
+    const sm = editor.getExtension(SuggestionMenu)!;
+
+    sm.addSuggestionMenu({ triggerCharacter: "img:" });
+
+    editor.replaceBlocks(editor.document, [
+      {
+        id: "paragraph-0",
+        type: "paragraph",
+        content: "hello img",
+      },
+    ]);
+
+    editor.setTextCursorPosition("paragraph-0", "end");
+
+    expect(getSuggestionPluginState(editor)).toBeUndefined();
+
+    const handled = simulateTextInput(editor, ":");
+
+    expect(handled).toBe(true);
+
+    const pluginState = getSuggestionPluginState(editor);
+    expect(pluginState).toBeDefined();
+    expect(pluginState.triggerCharacter).toBe("img:");
+
+    editor._tiptapEditor.destroy();
+  });
 });
diff --git a/packages/core/src/extensions/SuggestionMenu/SuggestionMenu.ts b/packages/core/src/extensions/SuggestionMenu/SuggestionMenu.ts
index 4809607e6e..d40de6d906 100644
--- a/packages/core/src/extensions/SuggestionMenu/SuggestionMenu.ts
+++ b/packages/core/src/extensions/SuggestionMenu/SuggestionMenu.ts
@@ -336,10 +336,19 @@ export const SuggestionMenu = createExtension(({ editor }) => {
             // only on insert
             if (from === to) {
               const doc = view.state.doc;
-              for (const [triggerChar, menuOptions] of suggestionMenus) {
+              // Match longer trigger characters first, so a multi-character
+              // trigger (e.g. "img:") wins over a single-character one (e.g.
+              // the default emoji ":") that would otherwise shadow it.
+              const orderedMenus = [...suggestionMenus].sort(
+                ([a], [b]) => b.length - a.length,
+              );
+              for (const [triggerChar, menuOptions] of orderedMenus) {
                 const snippet =
                   triggerChar.length > 1
-                    ? doc.textBetween(from - triggerChar.length, from) + text
+                    ? // The already-typed prefix is the first `length - 1`
+                      // chars; `text` is the final char being inserted now.
+                      doc.textBetween(from - (triggerChar.length - 1), from) +
+                      text
                     : text;
 
                 if (triggerChar === snippet) {