diff --git a/NEWS b/NEWS
index 4ace7d3dc462..756fd78bb8ac 100644
--- a/NEWS
+++ b/NEWS
@@ -62,6 +62,8 @@ PHP                                                                        NEWS
   . Fixed bug GH-20426 (Spoofchecker::setRestrictionLevel() error message
     suggests missing constants). (DanielEScherzer)
   . Added grapheme_strrev (Yuya Hamada)
+  . IntlDateFormatter::format() now accepts numeric-castable objects as
+    date/time values. (Weilin Du)
 
 - JSON:
   . Enriched JSON last error / exception message with error location.
diff --git a/UPGRADING b/UPGRADING
index d271eb47f7d1..297654e7235a 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -200,6 +200,10 @@ PHP 8.6 UPGRADE NOTES
   . gmp_powm() modulo-by-zero now raises a DivisionByZeroError whose
     message includes the function name and argument index ($modulus).
 
+- Intl:
+  . IntlDateFormatter::format() now accepts objects that support numeric
+    casting as date/time values.
+
 - mysqli:
   . The return structure of mysqli_get_charset() no longer contains
     the undocumented "comment" element. The value of "charsetnr" is
diff --git a/ext/intl/common/common_date.cpp b/ext/intl/common/common_date.cpp
index 0a7aa023b43c..36f0cd18a9c3 100644
--- a/ext/intl/common/common_date.cpp
+++ b/ext/intl/common/common_date.cpp
@@ -202,10 +202,28 @@ U_CFUNC double intl_zval_to_millis(zval *z, intl_error *err)
 				}
 			}
 		} else {
-			/* TODO: try with cast(), get() to obtain a number */
-			intl_errors_set(err, U_ILLEGAL_ARGUMENT_ERROR,
-				"invalid object type for date/time "
-				"(only IntlCalendar and DateTimeInterface permitted)");
+			zval casted;
+			ZVAL_UNDEF(&casted);
+
+			if (Z_OBJ_HT_P(z)->cast_object(Z_OBJ_P(z), &casted, _IS_NUMBER) == SUCCESS) {
+				if (EG(exception)) {
+				} else if (Z_TYPE(casted) == IS_LONG) {
+					rv = U_MILLIS_PER_SECOND * (double)Z_LVAL(casted);
+				} else if (Z_TYPE(casted) == IS_DOUBLE) {
+					rv = U_MILLIS_PER_SECOND * Z_DVAL(casted);
+				} else {
+					intl_errors_set(err, U_ILLEGAL_ARGUMENT_ERROR,
+						"invalid object type for date/time "
+						"(IntlCalendar, DateTimeInterface, or numeric-castable object permitted)");
+				}
+			} else if (!EG(exception)) { 
+				intl_errors_set(err, U_ILLEGAL_ARGUMENT_ERROR,
+					"invalid object type for date/time "
+					"(IntlCalendar, DateTimeInterface, or numeric-castable object permitted)");
+			}
+			if (!Z_ISUNDEF(casted)) {
+				zval_ptr_dtor(&casted);
+			}
 		}
 		break;
 	case IS_REFERENCE:
diff --git a/ext/intl/tests/dateformat_formatObject_numeric_object.phpt b/ext/intl/tests/dateformat_formatObject_numeric_object.phpt
new file mode 100644
index 000000000000..b2a9a02f6bc8
--- /dev/null
+++ b/ext/intl/tests/dateformat_formatObject_numeric_object.phpt
@@ -0,0 +1,24 @@
+--TEST--
+IntlDateFormatter->format(): numeric-castable objects
+--EXTENSIONS--
+intl
+zend_test
+--INI--
+intl.default_locale=en_US
+date.timezone=UTC
+--FILE--
+<?php
+
+$fmt = new IntlDateFormatter('en_US', IntlDateFormatter::NONE, IntlDateFormatter::NONE, 'UTC', null, 'yyyy-MM-dd HH:mm:ss.SSS');
+
+echo $fmt->format(new NumericCastableNoOperations(0)), "\n";
+echo datefmt_format($fmt, new NumericCastableNoOperations(0.5)), "\n";
+var_dump($fmt->format(new stdClass()));
+var_dump(intl_get_error_message());
+
+?>
+--EXPECT--
+1970-01-01 00:00:00.000
+1970-01-01 00:00:00.500
+bool(false)
+string(160) "IntlDateFormatter::format(): invalid object type for date/time (IntlCalendar, DateTimeInterface, or numeric-castable object permitted): U_ILLEGAL_ARGUMENT_ERROR"
diff --git a/ext/intl/tests/dateformat_format_error.phpt b/ext/intl/tests/dateformat_format_error.phpt
index 4358271efd08..f83f8250143e 100644
--- a/ext/intl/tests/dateformat_format_error.phpt
+++ b/ext/intl/tests/dateformat_format_error.phpt
@@ -21,6 +21,6 @@ var_dump(intl_get_error_message());
 ?>
 --EXPECT--
 bool(false)
-string(140) "IntlDateFormatter::format(): invalid object type for date/time (only IntlCalendar and DateTimeInterface permitted): U_ILLEGAL_ARGUMENT_ERROR"
+string(160) "IntlDateFormatter::format(): invalid object type for date/time (IntlCalendar, DateTimeInterface, or numeric-castable object permitted): U_ILLEGAL_ARGUMENT_ERROR"
 bool(false)
-string(129) "datefmt_format(): invalid object type for date/time (only IntlCalendar and DateTimeInterface permitted): U_ILLEGAL_ARGUMENT_ERROR"
+string(149) "datefmt_format(): invalid object type for date/time (IntlCalendar, DateTimeInterface, or numeric-castable object permitted): U_ILLEGAL_ARGUMENT_ERROR"