diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectionHelper.java b/spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectionHelper.java
index b0f2943b6f6..10854120d5d 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectionHelper.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectionHelper.java
@@ -314,11 +314,14 @@ public abstract class ReflectionHelper {
 				// convert it or wrap it in an array. For example, using StringToArrayConverter to convert
 				// a String containing a comma would result in the String being split and repackaged in an
 				// array when it should be used as-is. Similarly, if the argument is an array that is
-				// assignable to the varargs array type, there is no need to convert it.
+				// assignable to the varargs array type, there is no need to convert it. However, if the
+				// argument is a java.util.List, we let the TypeConverter convert the list to an array.
 				else if (!sourceType.isAssignableTo(componentTypeDesc) ||
-						(sourceType.isArray() && !sourceType.isAssignableTo(targetType))) {
+						(sourceType.isArray() && !sourceType.isAssignableTo(targetType)) ||
+						(argument instanceof List)) {
 
-					TypeDescriptor targetTypeToUse = (sourceType.isArray() ? targetType : componentTypeDesc);
+					TypeDescriptor targetTypeToUse =
+							(sourceType.isArray() || argument instanceof List ? targetType : componentTypeDesc);
 					arguments[varargsPosition] = converter.convertValue(argument, sourceType, targetTypeToUse);
 				}
 				// Possible outcomes of the above if-else block:
@@ -413,11 +416,14 @@ public abstract class ReflectionHelper {
 				// convert it. For example, using StringToArrayConverter to convert a String containing a
 				// comma would result in the String being split and repackaged in an array when it should
 				// be used as-is. Similarly, if the argument is an array that is assignable to the varargs
-				// array type, there is no need to convert it.
+				// array type, there is no need to convert it. However, if the argument is a java.util.List,
+				// we let the TypeConverter convert the list to an array.
 				else if (!sourceType.isAssignableTo(varargsComponentType) ||
-						(sourceType.isArray() && !sourceType.isAssignableTo(varargsArrayType))) {
+						(sourceType.isArray() && !sourceType.isAssignableTo(varargsArrayType)) ||
+						(argument instanceof List)) {
 
-					TypeDescriptor targetTypeToUse = (sourceType.isArray() ? varargsArrayType : varargsComponentType);
+					TypeDescriptor targetTypeToUse =
+							(sourceType.isArray() || argument instanceof List ? varargsArrayType : varargsComponentType);
 					arguments[varargsPosition] = converter.convertValue(argument, sourceType, targetTypeToUse);
 				}
 				// Possible outcomes of the above if-else block:
diff --git a/spring-expression/src/test/java/org/springframework/expression/spel/MethodInvocationTests.java b/spring-expression/src/test/java/org/springframework/expression/spel/MethodInvocationTests.java
index 6782245d262..3da7456189d 100644
--- a/spring-expression/src/test/java/org/springframework/expression/spel/MethodInvocationTests.java
+++ b/spring-expression/src/test/java/org/springframework/expression/spel/MethodInvocationTests.java
@@ -32,6 +32,7 @@ import org.springframework.expression.MethodResolver;
 import org.springframework.expression.spel.standard.SpelExpression;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
+import org.springframework.expression.spel.support.StandardTypeLocator;
 import org.springframework.expression.spel.testresources.Inventor;
 import org.springframework.expression.spel.testresources.PlaceOfBirth;
 
@@ -364,6 +365,21 @@ class MethodInvocationTests extends AbstractExpressionTests {
 		evaluate("formatObjectVarargs('x -> %s %s %s', new int[]{1, 2, 3})", "x -> 1 2 3", String.class); // int[] to Object[]
 	}
 
+	@Test  // gh-33315
+	void varargsWithListConvertedToVarargsArray() {
+		((StandardTypeLocator) context.getTypeLocator()).registerImport("java.util");
+
+		// Calling 'public String aVarargsMethod(String... strings)' -> Arrays.toString(strings)
+		String expected = "[a, b, c]";
+		evaluate("aVarargsMethod(T(List).of('a', 'b', 'c'))", expected, String.class);
+		evaluate("aVarargsMethod({'a', 'b', 'c'})", expected, String.class);
+
+		// Calling 'public String formatObjectVarargs(String format, Object... args)' -> String.format(format, args)
+		expected = "x -> a b c";
+		evaluate("formatObjectVarargs('x -> %s %s %s', T(List).of('a', 'b', 'c'))", expected, String.class);
+		evaluate("formatObjectVarargs('x -> %s %s %s', {'a', 'b', 'c'})", expected, String.class);
+	}
+
 	@Test
 	void varargsOptionalInvocation() {
 		// Calling 'public String optionalVarargsMethod(Optional<String>... values)'
diff --git a/spring-expression/src/test/java/org/springframework/expression/spel/VariableAndFunctionTests.java b/spring-expression/src/test/java/org/springframework/expression/spel/VariableAndFunctionTests.java
index c4af0e4ad8b..29a4255254a 100644
--- a/spring-expression/src/test/java/org/springframework/expression/spel/VariableAndFunctionTests.java
+++ b/spring-expression/src/test/java/org/springframework/expression/spel/VariableAndFunctionTests.java
@@ -20,6 +20,7 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
+import org.springframework.expression.spel.support.StandardTypeLocator;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -211,6 +212,33 @@ class VariableAndFunctionTests extends AbstractExpressionTests {
 		evaluate("#formatObjectVarargs('x -> %s %s %s', new int[]{1, 2, 3})", "x -> 1 2 3", String.class); // int[] to Object[]
 	}
 
+	@Test  // gh-33315
+	void functionFromMethodWithListConvertedToVarargsArray() {
+		((StandardTypeLocator) context.getTypeLocator()).registerImport("java.util");
+		String expected = "[a, b, c]";
+
+		evaluate("#varargsFunction(T(List).of('a', 'b', 'c'))", expected, String.class);
+		evaluate("#varargsFunction({'a', 'b', 'c'})", expected, String.class);
+
+		// Calling 'public String formatObjectVarargs(String format, Object... args)' -> String.format(format, args)
+		evaluate("#varargsObjectFunction(T(List).of('a', 'b', 'c'))", expected, String.class);
+		evaluate("#varargsObjectFunction({'a', 'b', 'c'})", expected, String.class);
+	}
+
+	@Test  // gh-33315
+	void functionFromMethodHandleWithListConvertedToVarargsArray() {
+		((StandardTypeLocator) context.getTypeLocator()).registerImport("java.util");
+		String expected = "x -> a b c";
+
+		// Calling 'public static String message(String template, String... args)' -> template.formatted((Object[]) args)
+		evaluate("#message('x -> %s %s %s', T(List).of('a', 'b', 'c'))", expected, String.class);
+		evaluate("#message('x -> %s %s %s', {'a', 'b', 'c'})", expected, String.class);
+
+		// Calling 'public static String formatObjectVarargs(String format, Object... args)' -> String.format(format, args)
+		evaluate("#formatObjectVarargs('x -> %s %s %s', T(List).of('a', 'b', 'c'))", expected, String.class);
+		evaluate("#formatObjectVarargs('x -> %s %s %s', {'a', 'b', 'c'})", expected, String.class);
+	}
+
 	@Test
 	void functionMethodMustBeStatic() throws Exception {
 		SpelExpressionParser parser = new SpelExpressionParser();