diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 83e43bff18d..89af872e8d6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -151,6 +151,11 @@ jobs:
               working-directory: extra/${{ matrix.extension }}
               run: "composer require --no-update 'symfony/translation-contracts:^1.1|^2.0'"
 
+            - name: "Prevent installing tempest/markdown, which requires PHP 8.5"
+              if: "matrix.extension == 'markdown-extra' && matrix.php-version != '8.5'"
+              working-directory: extra/${{ matrix.extension }}
+              run: composer remove --dev --no-update tempest/markdown
+
             - name: "Composer install ${{ matrix.extension }}"
               working-directory: extra/${{ matrix.extension }}
               run: composer install
diff --git a/.gitignore b/.gitignore
index b197246ba80..35ce42ad147 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,4 +3,5 @@
 /composer.lock
 /phpunit.xml
 /vendor
+.php-cs-fixer.cache
 .phpunit.result.cache
diff --git a/CHANGELOG b/CHANGELOG
index 1e8067d1fe9..cf0c97ecff1 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,6 @@
 # 3.29.0 (2026-XX-XX)
 
+ * Add `TempestMarkdown` to use `tempest/markdown` as the `markdown_to_html` converter
  * Fix imported macros not resolving their own template-level macro imports
  * Add the `Twig\Sandbox\SandboxInterface` interface and `Twig\Sandbox\Sandbox` class to render untrusted templates through a dedicated, always-sandboxed environment crafted for it
  * Add the `Twig\Extension\SandboxBridgeExtension` to render sandboxed templates from trusted templates with an explicit output escaping strategy
diff --git a/doc/filters/markdown_to_html.rst b/doc/filters/markdown_to_html.rst
index 780f0112b96..4218ed37ce2 100644
--- a/doc/filters/markdown_to_html.rst
+++ b/doc/filters/markdown_to_html.rst
@@ -84,10 +84,11 @@ Using a Custom Converter
 The ``markdown_to_html`` filter delegates the conversion to a class implementing
 ``Twig\Extra\Markdown\MarkdownInterface``. Several implementations are provided:
 ``LeagueMarkdown`` (``league/commonmark``), ``MichelfMarkdown``
-(``michelf/php-markdown``), and ``ErusevMarkdown`` (``erusev/parsedown``). Each
-accepts a pre-configured converter in its constructor, so you can tune the
-underlying library or switch to another implementation (for instance
-``ParsedownExtra``, which extends ``Parsedown``)::
+(``michelf/php-markdown``), ``ErusevMarkdown`` (``erusev/parsedown``), and
+``TempestMarkdown`` (``tempest/markdown``). Each accepts a pre-configured
+converter in its constructor, so you can tune the underlying library or switch
+to another implementation (for instance ``ParsedownExtra``, which extends
+``Parsedown``)::
 
     use Twig\Extra\Markdown\ErusevMarkdown;
 
@@ -96,6 +97,14 @@ underlying library or switch to another implementation (for instance
 
     $markdown = new ErusevMarkdown($parsedown);
 
+.. note::
+
+    ``tempest/markdown`` requires PHP 8.5 or later. It also differs from the
+    other libraries on two points worth knowing about: Setext headings
+    (``Title`` underlined with ``===``) are not supported, so use ATX headings
+    (``# Title``) instead, and any YAML front matter is parsed out of the
+    rendered HTML rather than being rendered.
+
 When using ``twig/extra-bundle``, register your converter as the
 ``twig.markdown.default`` service to make it the one used by the filter:
 
diff --git a/extra/markdown-extra/DefaultMarkdown.php b/extra/markdown-extra/DefaultMarkdown.php
index a20993d45da..38902208219 100644
--- a/extra/markdown-extra/DefaultMarkdown.php
+++ b/extra/markdown-extra/DefaultMarkdown.php
@@ -13,6 +13,7 @@
 
 use League\CommonMark\CommonMarkConverter;
 use Michelf\MarkdownExtra;
+use Tempest\Markdown\Markdown;
 
 class DefaultMarkdown implements MarkdownInterface
 {
@@ -26,6 +27,8 @@ public function __construct()
             $this->converter = new MichelfMarkdown();
         } elseif (class_exists(\Parsedown::class)) {
             $this->converter = new ErusevMarkdown();
+        } elseif (class_exists(Markdown::class)) {
+            $this->converter = new TempestMarkdown();
         } else {
             throw new \LogicException('You cannot use the "markdown_to_html" filter as no Markdown library is available; try running "composer require league/commonmark".');
         }
diff --git a/extra/markdown-extra/TempestMarkdown.php b/extra/markdown-extra/TempestMarkdown.php
new file mode 100644
index 00000000000..1e037ac998b
--- /dev/null
+++ b/extra/markdown-extra/TempestMarkdown.php
@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Twig\Extra\Markdown;
+
+use Tempest\Markdown\Markdown;
+
+class TempestMarkdown implements MarkdownInterface
+{
+    private $converter;
+
+    public function __construct(?Markdown $converter = null)
+    {
+        $this->converter = $converter ?: new Markdown();
+    }
+
+    public function convert(string $body): string
+    {
+        return $this->converter->parse($body)->html;
+    }
+}
diff --git a/extra/markdown-extra/Tests/FunctionalTest.php b/extra/markdown-extra/Tests/FunctionalTest.php
index 863221d189b..6fc57d86c28 100644
--- a/extra/markdown-extra/Tests/FunctionalTest.php
+++ b/extra/markdown-extra/Tests/FunctionalTest.php
@@ -20,6 +20,7 @@
 use Twig\Extra\Markdown\MarkdownInterface;
 use Twig\Extra\Markdown\MarkdownRuntime;
 use Twig\Extra\Markdown\MichelfMarkdown;
+use Twig\Extra\Markdown\TempestMarkdown;
 use Twig\Loader\ArrayLoader;
 use Twig\RuntimeLoader\RuntimeLoaderInterface;
 
@@ -30,12 +31,16 @@ class FunctionalTest extends TestCase
      */
     public function testMarkdown(string $template, string $expected): void
     {
-        foreach ([LeagueMarkdown::class, ErusevMarkdown::class, /* MichelfMarkdown::class, */ DefaultMarkdown::class] as $class) {
+        $classes = [LeagueMarkdown::class, ErusevMarkdown::class, /* MichelfMarkdown::class, */ DefaultMarkdown::class];
+        if (class_exists(\Tempest\Markdown\Markdown::class)) {
+            $classes[] = TempestMarkdown::class;
+        }
+
+        foreach ($classes as $class) {
             $twig = new Environment(new ArrayLoader([
                 'index' => $template,
                 'html' => <<<EOF
-Hello
-=====
+# Hello
 
 Great!
 EOF,
@@ -63,21 +68,19 @@ public static function getMarkdownTests()
         return [
             [<<<EOF
 {% apply markdown_to_html %}
-Hello
-=====
+# Hello
 
 Great!
 {% endapply %}
-EOF, "<h1>Hello</h1>\n+<p>Great!</p>"],
+EOF, "<h1[^>]*>Hello</h1>\n+<p>Great!\s*</p>"],
             [<<<EOF
 {% apply markdown_to_html %}
-    Hello
-    =====
+    # Hello
 
     Great!
 {% endapply %}
-EOF, "<h1>Hello</h1>\n+<p>Great!</p>"],
-            ["{{ include('html')|markdown_to_html }}", "<h1>Hello</h1>\n+<p>Great!</p>"],
+EOF, "<h1[^>]*>Hello</h1>\n+<p>Great!\s*</p>"],
+            ["{{ include('html')|markdown_to_html }}", "<h1[^>]*>Hello</h1>\n+<p>Great!\s*</p>"],
             [<<<EOF
 {% apply markdown_to_html %}
 
@@ -85,7 +88,7 @@ public static function getMarkdownTests()
 
 Paragraph 2
 {% endapply %}
-EOF, "<p>Paragraph 1</p>\n+<p>Paragraph 2</p>"],
+EOF, "<p>Paragraph 1</p>\n+<p>Paragraph 2\s*</p>"],
         ];
     }
 
diff --git a/extra/markdown-extra/composer.json b/extra/markdown-extra/composer.json
index 703b25c20fb..1d92d7575ee 100644
--- a/extra/markdown-extra/composer.json
+++ b/extra/markdown-extra/composer.json
@@ -24,7 +24,8 @@
         "erusev/parsedown": "dev-master as 1.x-dev",
         "league/commonmark": "^2.7",
         "league/html-to-markdown": "^4.8|^5.0",
-        "michelf/php-markdown": "^1.8|^2.0"
+        "michelf/php-markdown": "^1.8|^2.0",
+        "tempest/markdown": "^1.2"
     },
     "autoload": {
         "files": [ "Resources/functions.php" ],