diff --git a/extra/html-extra/HtmlExtension.php b/extra/html-extra/HtmlExtension.php
index d8a6c0036d1..b01cc49e56a 100644
--- a/extra/html-extra/HtmlExtension.php
+++ b/extra/html-extra/HtmlExtension.php
@@ -12,8 +12,10 @@
 namespace Twig\Extra\Html;
 
 use Symfony\Component\Mime\MimeTypes;
+use Twig\Environment;
 use Twig\Error\RuntimeError;
 use Twig\Extension\AbstractExtension;
+use Twig\Runtime\EscaperRuntime;
 use Twig\TwigFilter;
 use Twig\TwigFunction;
 
@@ -30,6 +32,7 @@ public function getFilters(): array
     {
         return [
             new TwigFilter('data_uri', [$this, 'dataUri']),
+            new TwigFilter('html_attr_merge', [self::class, 'htmlAttrMerge']),
         ];
     }
 
@@ -38,6 +41,7 @@ public function getFunctions(): array
         return [
             new TwigFunction('html_classes', [self::class, 'htmlClasses']),
             new TwigFunction('html_cva', [self::class, 'htmlCva']),
+            new TwigFunction('html_attr', [self::class, 'htmlAttr'], ['needs_environment' => true, 'is_safe' => ['html']]),
         ];
     }
 
@@ -124,4 +128,96 @@ public static function htmlCva(array|string $base = [], array $variants = [], ar
     {
         return new Cva($base, $variants, $compoundVariants, $defaultVariant);
     }
+
+    public static function htmlAttrMerge(...$arrays): array
+    {
+        $result = [];
+
+        foreach ($arrays as $argNumber => $array) {
+            if (!$array) {
+                continue;
+            }
+
+            if (!is_iterable($array)) {
+                throw new RuntimeError(sprintf('The "attr_merge" filter only works with mappings or "Traversable", got "%s" for argument %d.', \gettype($array), $argNumber + 1));
+            }
+
+            $array = (array) ($array);
+
+            foreach (['data', 'aria'] as $flatOutKey) {
+                if (!isset($array[$flatOutKey])) {
+                    continue;
+                }
+                $values = (array) $array[$flatOutKey];
+                foreach ($values as $key => $value) {
+                    $result[$flatOutKey.'-'.$key] = $value;
+                }
+                unset($array[$flatOutKey]);
+            }
+
+            foreach (['class', 'style'] as $deepMergeKey) {
+                if (!isset($array[$deepMergeKey])) {
+                    continue;
+                }
+
+                $value = $array[$deepMergeKey];
+                unset($array[$deepMergeKey]);
+
+                if (!is_iterable($value)) {
+                    $value = (array) $value;
+                }
+
+                $result[$deepMergeKey] = [...$result[$deepMergeKey] ?? [], ...$value];
+            }
+
+            $result = [...$result, ...$array];
+        }
+
+        return $result;
+    }
+
+    public static function htmlAttr(Environment $env, ...$args): string
+    {
+        $attr = self::htmlAttrMerge(...$args);
+
+        if (isset($attr['class'])) {
+            $attr['class'] = trim(implode(' ', $attr['class']));
+        }
+
+        if (isset($attr['style'])) {
+            $style = '';
+            foreach ($attr['style'] as $name => $value) {
+                if (is_numeric($name)) {
+                    $style .= $value.'; ';
+                } else {
+                    $style .= $name.': '.$value.'; ';
+                }
+            }
+            $attr['style'] = trim($style);
+        }
+
+        if (isset($attr['data'])) {
+            foreach ($attr['data'] as $name => $value) {
+                $attr['data-'.$name] = $value;
+            }
+            unset($attr['data']);
+        }
+
+        $result = '';
+        $runtime = $env->getRuntime(EscaperRuntime::class);
+
+        foreach ($attr as $name => $value) {
+            if ($value === false) {
+                continue;
+            }
+
+            if ($value === true) {
+                $value = $name;
+            }
+
+            $result .= $runtime->escape($name, 'html_attr').'="'.$runtime->escape($value).'" ';
+        }
+
+        return trim($result);
+    }
 }
diff --git a/extra/html-extra/Tests/Fixtures/html_attr_merge.test b/extra/html-extra/Tests/Fixtures/html_attr_merge.test
new file mode 100644
index 00000000000..108f216ac6b
--- /dev/null
+++ b/extra/html-extra/Tests/Fixtures/html_attr_merge.test
@@ -0,0 +1,19 @@
+--TEST--
+"html_attr_merge" function
+--TEMPLATE--
+{% autoescape false %}
+#1 - {{ { foo: 'bar' } | html_attr_merge({ bar: 'baz' }) | json_encode }}
+#2 - {{ { class: 'foo' } | html_attr_merge({ class: 'bar' })  | json_encode }}
+#3 - {{ { class: 'foo' } | html_attr_merge({ class: ['bar', 'baz'] })  | json_encode }}
+#4 - {{ { class: { special: 'foo' } }
+    | html_attr_merge({ class: ['bar', 'baz'] })
+    | html_attr_merge({ class: { special: 'qux' } })
+    | json_encode }}
+{% endautoescape %}
+--DATA--
+return []
+--EXPECT--
+#1 - {"foo":"bar","bar":"baz"}
+#2 - {"class":["foo","bar"]}
+#3 - {"class":["foo","bar","baz"]}
+#4 - {"class":{"special":"qux","0":"bar","1":"baz"}}
diff --git a/extra/html-extra/Tests/HtmlAttrMergeTest.php b/extra/html-extra/Tests/HtmlAttrMergeTest.php
new file mode 100644
index 00000000000..28839c448f5
--- /dev/null
+++ b/extra/html-extra/Tests/HtmlAttrMergeTest.php
@@ -0,0 +1,184 @@
+<?php
+
+namespace Twig\Extra\Html\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Twig\Extra\Html\HtmlExtension;
+
+class HtmlAttrMergeTest extends TestCase
+{
+    /**
+     * @dataProvider htmlAttrProvider
+     */
+    public function testMerge(array $expected, array $inputs)
+    {
+        $result = HtmlExtension::htmlAttrMerge(...$inputs);
+
+        self::assertSame($expected, $result);
+    }
+
+    public function htmlAttrProvider(): \Generator
+    {
+        yield 'merging different attributes from two arrays' => [
+            ['id' => 'some-id', 'label' => 'some-label'],
+            [
+                ['id' => 'some-id'],
+                ['label' => 'some-label'],
+            ]
+        ];
+
+        yield 'merging different attributes from three arrays' => [
+            ['id' => 'some-id', 'label' => 'some-label', 'role' => 'main'],
+            [
+                ['id' => 'some-id'],
+                ['label' => 'some-label'],
+                ['role' => 'main'],
+            ]
+        ];
+
+        yield 'merging different attributes from Traversables' => [
+            ['id' => 'some-id', 'label' => 'some-label', 'role' => 'main'],
+            [
+                new \ArrayIterator(['id' => 'some-id']),
+                new \ArrayIterator(['label' => 'some-label']),
+                new \ArrayIterator(['role' => 'main']),
+            ]
+        ];
+
+        yield 'later keys override previous ones' => [
+            ['id' => 'other'],
+            [
+                ['id' => 'this'],
+                ['id' => 'that'],
+                ['id' => 'other'],
+            ]
+        ];
+
+        yield 'ignore empty strings or arrays passed as arguments' => [
+            ['some' => 'attribute'],
+            [
+                ['some' => 'attribute'],
+                [], // empty array
+                '', // empty string
+            ]
+        ];
+
+        yield 'keep "true" and "false" boolean values' => [
+            ['disabled' => true, 'enabled' => false],
+            [
+                ['disabled' => true],
+                ['enabled' => false],
+            ]
+        ];
+
+        yield 'consolidate values for the "class" key' => [
+            ['class' => ['foo', 'bar', 'baz']],
+            [
+                ['class' => ['foo']],
+                ['class' => 'bar'], // string, not array
+                ['class' => ['baz']],
+            ]
+        ];
+
+        yield 'class values can be overridden when they use names (array keys)' => [
+            ['class' => ['foo', 'bar', 'importance' => 'high']],
+            [
+                ['class' => 'foo'],
+                ['class' => ['bar', 'importance' => 'low']],
+                ['class' => ['importance' => 'high']],
+            ]
+        ];
+
+        yield 'inline style values with numerical keys are merely collected' => [
+            ['style' => ['font-weight: light', 'color: green', 'font-weight: bold']],
+            [
+                ['style' => ['font-weight: light']],
+                ['style' => ['color: green', 'font-weight: bold']],
+            ]
+        ];
+
+        yield 'inline style values can be overridden when they use names (array keys)' => [
+            ['style' => ['font-weight' => 'bold', 'color' => 'red']],
+            [
+                ['style' => ['font-weight' => 'light']],
+                ['style' => ['color' => 'green', 'font-weight' => 'bold']],
+                ['style' => ['color' => 'red']],
+            ]
+        ];
+
+        yield 'no merging happens when mixing numerically indexed inline styles with named ones' => [
+            ['style' => ['color: green', 'color' => 'red']],
+            [
+                ['style' => ['color: green']],
+                ['style' => ['color' => 'red']],
+            ]
+        ];
+
+        yield 'turning aria attributes from array to flat keys' => [
+            ['aria-role' => 'banner'],
+            [
+                ['aria' => ['role' => 'main']],
+                ['aria' => ['role' => 'banner']],
+            ]
+        ];
+
+        yield 'using aria attributes from a sub-array' => [
+            ['aria-role' => 'main', 'aria-label' => 'none'],
+            [
+                ['aria' => ['role' => 'main', 'label' => 'none']],
+            ]
+        ];
+
+        yield 'merging aria attributes, where the array values overrides the flat one' => [
+            ['aria-role' => 'navigation'],
+            [
+                ['aria-role' => 'main'],
+                ['aria' => ['role' => 'banner']],
+                ['aria' => ['role' => 'navigation']],
+            ]
+        ];
+
+        yield 'merging aria attributes, where the flat ones overrides the array' => [
+            ['aria-role' => 'navigation'],
+            [
+                ['aria' => ['role' => 'main']],
+                ['aria-role' => 'banner'],
+                ['aria-role' => 'navigation'],
+            ]
+        ];
+
+        yield 'using data attributes in a sub-array' => [
+            ['data-foo' => 'this', 'data-bar' => 'that'],
+            [
+                ['data' => ['foo' => 'this']],
+                ['data' => ['bar' => 'that']],
+            ]
+        ];
+
+        yield 'turning data attributes from array to flat keys' => [
+            ['data-test' => 'bar'],
+            [
+                ['data' => ['test' => 'foo']],
+                ['data' => ['test' => 'bar']],
+            ]
+        ];
+
+        yield 'merging data attributes, where the array values overrides the flat one' => [
+            ['data-test' => 'baz'],
+            [
+                ['data-test' => 'foo'],
+                ['data' => ['test' => 'bar']],
+                ['data' => ['test' => 'baz']],
+            ]
+        ];
+
+        yield 'merging data attributes, where the flat ones overrides the array' => [
+            ['data-test' => 'baz'],
+            [
+                ['data' => ['test' => 'foo']],
+                ['data-test' => 'bar'],
+                ['data-test' => 'baz'],
+            ]
+        ];
+    }
+}