diff --git a/packages/lexical-markdown/src/MarkdownTransformers.ts b/packages/lexical-markdown/src/MarkdownTransformers.ts
index 0fc245c81b5..994b691bd4c 100644
--- a/packages/lexical-markdown/src/MarkdownTransformers.ts
+++ b/packages/lexical-markdown/src/MarkdownTransformers.ts
@@ -222,6 +222,7 @@ const ORDERED_LIST_REGEX = /^(\s*)(\d{1,})\.\s/;
 const UNORDERED_LIST_REGEX = /^(\s*)[-*+]\s/;
 const CHECK_LIST_REGEX = /^(\s*)(?:[-*+]\s)?\s?(\[(\s|x)?\])\s/i;
 const HEADING_REGEX = /^(#{1,6})\s/;
+const HEADING_CLOSING_SEQUENCE_REGEX = /(?:^|[ \t]+)#+[ \t]*$/;
 const QUOTE_REGEX = /^>\s/;
 const CODE_START_REGEX = /^([ \t]*`{3,})([\w-]+)?[ \t]?/;
 const CODE_END_REGEX = /^[ \t]*`{3,}$/;
@@ -807,6 +808,20 @@ export const HEADING: ElementTransformer = {
     if (!isImport && $isUnreplaceableBlock(parentNode)) {
       return false;
     }
+    if (isImport) {
+      // An ATX heading may end with a closing sequence of `#`s, which is not
+      // part of the content: `## Hello ##` is a heading reading "Hello".
+      // The sequence must be preceded by a space or tab (or be the whole
+      // content); `# C#` keeps its `#`.
+      const lastChild = children[children.length - 1];
+      if ($isTextNode(lastChild)) {
+        const text = lastChild.getTextContent();
+        const stripped = text.replace(HEADING_CLOSING_SEQUENCE_REGEX, '');
+        if (stripped !== text) {
+          lastChild.setTextContent(stripped);
+        }
+      }
+    }
     return $replaceWithHeading(parentNode, children, match, isImport);
   },
   triggerOnEnter: true,
diff --git a/packages/lexical-markdown/src/__tests__/unit/LexicalMarkdown.test.ts b/packages/lexical-markdown/src/__tests__/unit/LexicalMarkdown.test.ts
index b7b6051268f..08123f5134a 100644
--- a/packages/lexical-markdown/src/__tests__/unit/LexicalMarkdown.test.ts
+++ b/packages/lexical-markdown/src/__tests__/unit/LexicalMarkdown.test.ts
@@ -342,6 +342,23 @@ describe('Markdown', () => {
       html: '<h6><span style="white-space: pre-wrap;">Hello world</span></h6>',
       md: '###### Hello world',
     },
+    {
+      // ATX closing sequence: https://spec.commonmark.org/0.31.2/#example-71
+      html: '<h2><span style="white-space: pre-wrap;">Hello world</span></h2>',
+      md: '## Hello world ##',
+      skipExport: true,
+    },
+    {
+      // The closing sequence may be any length and followed by spaces
+      html: '<h1><span style="white-space: pre-wrap;">Hello world</span></h1>',
+      md: '# Hello world #####   ',
+      skipExport: true,
+    },
+    {
+      // A `#` not preceded by a space is content, not a closing sequence
+      html: '<h1><span style="white-space: pre-wrap;">Hello C#</span></h1>',
+      md: '# Hello C#',
+    },
     {
       // Multiline paragraphs: https://spec.commonmark.org/dingus/?text=Hello%0Aworld%0A!
       html: '<p><span style="white-space: pre-wrap;">Hello world !</span></p>',