diff --git a/CHANGELOG b/CHANGELOG
index 72e77863465..ba4b573764d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,6 @@
 # 3.29.0 (2026-XX-XX)
 
+ * Fix `IntlExtension` ignoring explicit date/time formats and the `format_date`/`format_time` filters when a date formatter prototype is configured
  * Add a `format_list` filter to `IntlExtension` to format a list of strings using PHP 8.5's `IntlListFormatter`
  * Fix array access with a `Stringable` key coercing the key to string for `ArrayAccess` objects that use object keys (such as `SplObjectStorage`)
  * Fix duplicated macro argument names triggering a PHP fatal error instead of a `SyntaxError`
diff --git a/extra/intl-extra/IntlExtension.php b/extra/intl-extra/IntlExtension.php
index cc740f6563c..c561c38d65d 100644
--- a/extra/intl-extra/IntlExtension.php
+++ b/extra/intl-extra/IntlExtension.php
@@ -405,7 +405,7 @@ public function formatNumberStyle(string $style, $number, array $attrs = [], str
      * @param \DateTimeInterface|string|null  $date     A date or null to use the current time
      * @param \DateTimeZone|string|false|null $timezone The target timezone, null to use the default, false to leave unchanged
      */
-    public function formatDateTime(Environment $env, $date, ?string $dateFormat = 'medium', ?string $timeFormat = 'medium', string $pattern = '', $timezone = null, string $calendar = 'gregorian', ?string $locale = null): string
+    public function formatDateTime(Environment $env, $date, ?string $dateFormat = null, ?string $timeFormat = null, string $pattern = '', $timezone = null, string $calendar = 'gregorian', ?string $locale = null): string
     {
         $date = $env->getExtension(CoreExtension::class)->convertDate($date, $timezone);
 
@@ -428,7 +428,7 @@ public function formatDateTime(Environment $env, $date, ?string $dateFormat = 'm
      * @param \DateTimeInterface|string|null  $date     A date or null to use the current time
      * @param \DateTimeZone|string|false|null $timezone The target timezone, null to use the default, false to leave unchanged
      */
-    public function formatDate(Environment $env, $date, ?string $dateFormat = 'medium', string $pattern = '', $timezone = null, string $calendar = 'gregorian', ?string $locale = null): string
+    public function formatDate(Environment $env, $date, ?string $dateFormat = null, string $pattern = '', $timezone = null, string $calendar = 'gregorian', ?string $locale = null): string
     {
         return $this->formatDateTime($env, $date, $dateFormat, 'none', $pattern, $timezone, $calendar, $locale);
     }
@@ -437,7 +437,7 @@ public function formatDate(Environment $env, $date, ?string $dateFormat = 'mediu
      * @param \DateTimeInterface|string|null  $date     A date or null to use the current time
      * @param \DateTimeZone|string|false|null $timezone The target timezone, null to use the default, false to leave unchanged
      */
-    public function formatTime(Environment $env, $date, ?string $timeFormat = 'medium', string $pattern = '', $timezone = null, string $calendar = 'gregorian', ?string $locale = null): string
+    public function formatTime(Environment $env, $date, ?string $timeFormat = null, string $pattern = '', $timezone = null, string $calendar = 'gregorian', ?string $locale = null): string
     {
         return $this->formatDateTime($env, $date, 'none', $timeFormat, $pattern, $timezone, $calendar, $locale);
     }
@@ -475,17 +475,24 @@ private function createDateFormatter(?string $locale, ?string $dateFormat, ?stri
 
         $calendar = 'gregorian' === $calendar ? \IntlDateFormatter::GREGORIAN : \IntlDateFormatter::TRADITIONAL;
 
-        $dateFormatValue = $dateFormats[$dateFormat] ?? null;
-        $timeFormatValue = self::TIME_FORMATS[$timeFormat] ?? null;
+        $dateFormatValue = null === $dateFormat ? null : $dateFormats[$dateFormat];
+        $timeFormatValue = null === $timeFormat ? null : self::TIME_FORMATS[$timeFormat];
 
         if ($this->dateFormatterPrototype) {
-            $dateFormatValue = $dateFormatValue ?: $this->dateFormatterPrototype->getDateType();
-            $timeFormatValue = $timeFormatValue ?: $this->dateFormatterPrototype->getTimeType();
+            $dateFormatValue ??= $this->dateFormatterPrototype->getDateType();
+            $timeFormatValue ??= $this->dateFormatterPrototype->getTimeType();
             $timezone = $timezone ?: $this->dateFormatterPrototype->getTimeZone()->toDateTimeZone();
             $calendar = $calendar ?: $this->dateFormatterPrototype->getCalendar();
-            $pattern = $pattern ?: $this->dateFormatterPrototype->getPattern();
+            // fall back to the prototype's pattern only when nothing else was given, else it would override the explicit date/time formats;
+            // a pattern describes a full datetime rendering, so it cannot be honored by format_date/format_time, which pass 'none' for the other part
+            if ('' === $pattern && null === $dateFormat && null === $timeFormat) {
+                $pattern = $this->dateFormatterPrototype->getPattern();
+            }
         }
 
+        $dateFormatValue ??= \IntlDateFormatter::MEDIUM;
+        $timeFormatValue ??= \IntlDateFormatter::MEDIUM;
+
         $timezoneName = $timezone ? $timezone->getName() : '(none)';
 
         $hash = $locale.'|'.$dateFormatValue.'|'.$timeFormatValue.'|'.$timezoneName.'|'.$calendar.'|'.$pattern;
diff --git a/extra/intl-extra/Tests/IntlExtensionTest.php b/extra/intl-extra/Tests/IntlExtensionTest.php
index e870b7c4f47..6c254d7af99 100644
--- a/extra/intl-extra/Tests/IntlExtensionTest.php
+++ b/extra/intl-extra/Tests/IntlExtensionTest.php
@@ -97,6 +97,32 @@ public function testFormatterOverridenProto(): void
         );
     }
 
+    public function testFormatterProtoDoesNotOverrideExplicitFormats(): void
+    {
+        $dateFormatterProto = new \IntlDateFormatter('nl_NL', \IntlDateFormatter::MEDIUM, \IntlDateFormatter::MEDIUM, new \DateTimeZone('Europe/Amsterdam'));
+        $ext = new IntlExtension($dateFormatterProto);
+        $env = new Environment(new ArrayLoader());
+        $date = new \DateTime('2020-02-20T22:22:00+00:00', new \DateTimeZone('UTC'));
+
+        $this->assertSame('20 feb 2020', $ext->formatDate($env, $date));
+        $this->assertSame('22:22:00', $ext->formatTime($env, $date));
+        $this->assertSame('donderdag 20 februari 2020', $ext->formatDateTime($env, $date, 'full', 'none'));
+    }
+
+    public function testFormatterProtoWithCustomPatternIsUsedByDefault(): void
+    {
+        $dateFormatterProto = new \IntlDateFormatter('nl_NL', \IntlDateFormatter::MEDIUM, \IntlDateFormatter::MEDIUM, new \DateTimeZone('Europe/Amsterdam'), \IntlDateFormatter::GREGORIAN, 'yyyy-MM-dd');
+        $ext = new IntlExtension($dateFormatterProto);
+        $env = new Environment(new ArrayLoader());
+        $date = new \DateTime('2020-02-20T22:22:00+00:00', new \DateTimeZone('UTC'));
+
+        $this->assertSame('2020-02-20', $ext->formatDateTime($env, $date));
+        $this->assertSame('20 feb 2020', $ext->formatDate($env, $date, 'medium'));
+        // the prototype pattern describes a full datetime rendering, so format_date/format_time ignore it
+        $this->assertSame('20 feb 2020', $ext->formatDate($env, $date));
+        $this->assertSame('22:22:00', $ext->formatTime($env, $date));
+    }
+
     public function testDateFormatterCacheIsBounded(): void
     {
         $ext = new IntlExtension();