diff --git a/.chronus/changes/http-client-java-cast-null-sample-arguments-2026-09-15.md b/.chronus/changes/http-client-java-cast-null-sample-arguments-2026-09-15.md
new file mode 100644
index 00000000000..3be7b203f1a
--- /dev/null
+++ b/.chronus/changes/http-client-java-cast-null-sample-arguments-2026-09-15.md
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/http-client-java"
+---
+
+Cast null arguments to their declared Java types in generated samples and tests so overloaded API calls are unambiguous.
\ No newline at end of file
diff --git a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ClientMethodExampleWriter.java b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ClientMethodExampleWriter.java
index 9a72c0e890d..a3dd6a8686d 100644
--- a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ClientMethodExampleWriter.java
+++ b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ClientMethodExampleWriter.java
@@ -60,11 +60,11 @@ public ClientMethodExampleWriter(ClientMethod method, String clientVarName, Prox
                 .filter(methodParameter -> !pageDetails.shouldHideParameter(methodParameter.getClientMethodParameter()))
                 .collect(Collectors.toList());
         }
-        List<ExampleNode> exampleNodes = methodParameters.stream()
-            .map(methodParameter -> parseNodeFromParameter(method, proxyMethodExample, methodParameter))
-            .collect(Collectors.toList());
-
-        String parameterInvocations = exampleNodes.stream().map(nodeVisitor::accept).collect(Collectors.joining(", "));
+        String parameterInvocations = methodParameters.stream()
+            .map(methodParameter -> ExampleWriterUtil.getParameterExpression(
+                methodParameter.getClientMethodParameter().getClientType(),
+                nodeVisitor.accept(parseNodeFromParameter(method, proxyMethodExample, methodParameter))))
+            .collect(Collectors.joining(", "));
 
         // assertion
         this.imports.add("org.junit.jupiter.api.Assertions");
diff --git a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ExampleWriterUtil.java b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ExampleWriterUtil.java
new file mode 100644
index 00000000000..f3eae5c9c0c
--- /dev/null
+++ b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ExampleWriterUtil.java
@@ -0,0 +1,15 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.microsoft.typespec.http.client.generator.core.template.example;
+
+import com.microsoft.typespec.http.client.generator.core.model.clientmodel.IType;
+
+final class ExampleWriterUtil {
+    private ExampleWriterUtil() {
+    }
+
+    static String getParameterExpression(IType parameterType, String valueExpression) {
+        return "null".equals(valueExpression) ? String.format("(%s) null", parameterType) : valueExpression;
+    }
+}
diff --git a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ProtocolExampleWriter.java b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ProtocolExampleWriter.java
index 9e6b72ec301..8d9377a5ccf 100644
--- a/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ProtocolExampleWriter.java
+++ b/packages/http-client-java/generator/http-client-generator-core/src/main/java/com/microsoft/typespec/http/client/generator/core/template/example/ProtocolExampleWriter.java
@@ -78,7 +78,8 @@ public ProtocolExampleWriter(ProtocolExample protocolExample) {
         // parameter values and required invocation on RequestOptions
         List<String> params = new ArrayList<>();
         for (ClientMethodParameter parameter : method.getParameters()) {
-            params.add(parameter.getClientType().defaultValueExpression());
+            params.add(ExampleWriterUtil.getParameterExpression(parameter.getClientType(),
+                parameter.getClientType().defaultValueExpression()));
         }
 
         StringBuilder binaryDataStmt = new StringBuilder();
diff --git a/packages/http-client-java/generator/http-client-generator-core/src/test/java/com/microsoft/typespec/http/client/generator/core/template/example/ExampleWriterUtilTests.java b/packages/http-client-java/generator/http-client-generator-core/src/test/java/com/microsoft/typespec/http/client/generator/core/template/example/ExampleWriterUtilTests.java
new file mode 100644
index 00000000000..7801c2506a0
--- /dev/null
+++ b/packages/http-client-java/generator/http-client-generator-core/src/test/java/com/microsoft/typespec/http/client/generator/core/template/example/ExampleWriterUtilTests.java
@@ -0,0 +1,20 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.microsoft.typespec.http.client.generator.core.template.example;
+
+import com.microsoft.typespec.http.client.generator.core.model.clientmodel.ClassType;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class ExampleWriterUtilTests {
+    @Test
+    public void typesNullParameterExpression() {
+        Assertions.assertEquals("(String) null", ExampleWriterUtil.getParameterExpression(ClassType.STRING, "null"));
+    }
+
+    @Test
+    public void preservesNonNullParameterExpression() {
+        Assertions.assertEquals("\"value\"", ExampleWriterUtil.getParameterExpression(ClassType.STRING, "\"value\""));
+    }
+}
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/builtin/generated/BuiltinOpRead.java b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/builtin/generated/BuiltinOpRead.java
index d6e2abe2255..49a732399af 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/builtin/generated/BuiltinOpRead.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/builtin/generated/BuiltinOpRead.java
@@ -5,6 +5,7 @@
 package tsptest.builtin.generated;
 
 import com.azure.core.util.Configuration;
+import java.time.OffsetDateTime;
 import tsptest.builtin.BuiltinClient;
 import tsptest.builtin.BuiltinClientBuilder;
 import tsptest.builtin.models.Builtin;
@@ -14,7 +15,8 @@ public static void main(String[] args) {
         BuiltinClient builtinClient
             = new BuiltinClientBuilder().endpoint(Configuration.getGlobalConfiguration().get("ENDPOINT")).buildClient();
         // BEGIN:tsptest.builtin.generated.builtin-op-read.builtin-op-read
-        Builtin response = builtinClient.read(null, null, null, "myFilter", null, null);
+        Builtin response = builtinClient.read((String) null, (String) null, (OffsetDateTime) null, "myFilter",
+            (String) null, (String) null);
         // END:tsptest.builtin.generated.builtin-op-read.builtin-op-read
     }
 }
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/flatten/generated/FlattenOpSend.java b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/flatten/generated/FlattenOpSend.java
index fca52e8cf66..9e5aef95871 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/flatten/generated/FlattenOpSend.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/flatten/generated/FlattenOpSend.java
@@ -14,7 +14,7 @@ public static void main(String[] args) {
         FlattenClient flattenClient
             = new FlattenClientBuilder().endpoint(Configuration.getGlobalConfiguration().get("ENDPOINT")).buildClient();
         // BEGIN:tsptest.flatten.generated.send.flatten-op-send
-        flattenClient.send("myRequiredId", null, "myRequiredInput", 0, 50, new User("myOptionalUser"));
+        flattenClient.send("myRequiredId", (String) null, "myRequiredInput", 0, 50, new User("myOptionalUser"));
         // END:tsptest.flatten.generated.send.flatten-op-send
     }
 }
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/model/generated/ModelOpPutNested.java b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/model/generated/ModelOpPutNested.java
index 8a31ccb2712..9527a3d8c35 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/model/generated/ModelOpPutNested.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/model/generated/ModelOpPutNested.java
@@ -14,7 +14,7 @@ public static void main(String[] args) {
         ModelClient modelClient
             = new ModelClientBuilder().endpoint(Configuration.getGlobalConfiguration().get("ENDPOINT")).buildClient();
         // BEGIN:tsptest.model.generated.model-op-put-nested.model-op-put-nested
-        NestedModel response = modelClient.putNested(null);
+        NestedModel response = modelClient.putNested((NestedModel) null);
         // END:tsptest.model.generated.model-op-put-nested.model-op-put-nested
     }
 }
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/specialchars/generated/BuiltinOpRead.java b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/specialchars/generated/BuiltinOpRead.java
index 4dd26ace46b..6b8396f7b2f 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/specialchars/generated/BuiltinOpRead.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/specialchars/generated/BuiltinOpRead.java
@@ -15,7 +15,7 @@ public static void main(String[] args) {
             = new SpecialCharsClientBuilder().endpoint(Configuration.getGlobalConfiguration().get("ENDPOINT"))
                 .buildClient();
         // BEGIN:tsptest.specialchars.generated.builtin-op-read.builtin-op-read
-        Resource response = specialCharsClient.read(null);
+        Resource response = specialCharsClient.read((String) null);
         // END:tsptest.specialchars.generated.builtin-op-read.builtin-op-read
     }
 }
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/versioning/generated/VersioningOpList.java b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/versioning/generated/VersioningOpList.java
index 85f33ac976f..b71870bc745 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/versioning/generated/VersioningOpList.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/samples/java/tsptest/versioning/generated/VersioningOpList.java
@@ -17,7 +17,7 @@ public static void main(String[] args) {
             = new VersioningClientBuilder().endpoint(Configuration.getGlobalConfiguration().get("ENDPOINT"))
                 .buildClient();
         // BEGIN:tsptest.versioning.generated.versioning-op-list.versioning-op-list
-        PagedIterable<Resource> response = versioningClient.list(Arrays.asList("name=name"), null);
+        PagedIterable<Resource> response = versioningClient.list(Arrays.asList("name=name"), (String) null);
         // END:tsptest.versioning.generated.versioning-op-list.versioning-op-list
     }
 }
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/builtin/generated/BuiltinOpReadTests.java b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/builtin/generated/BuiltinOpReadTests.java
index 8fa08f909c1..5d7c1819674 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/builtin/generated/BuiltinOpReadTests.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/builtin/generated/BuiltinOpReadTests.java
@@ -4,6 +4,7 @@
 
 package tsptest.builtin.generated;
 
+import java.time.OffsetDateTime;
 import java.util.List;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Disabled;
@@ -17,7 +18,8 @@ public final class BuiltinOpReadTests extends BuiltinClientTestBase {
     @Disabled
     public void testBuiltinOpReadTests() {
         // method invocation
-        Builtin response = builtinClient.read(null, null, null, "myFilter", null, null);
+        Builtin response = builtinClient.read((String) null, (String) null, (OffsetDateTime) null, "myFilter",
+            (String) null, (String) null);
 
         // response assertion
         Assertions.assertNotNull(response);
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/flatten/generated/FlattenOpSendTests.java b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/flatten/generated/FlattenOpSendTests.java
index a968457260e..0e1eadc6385 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/flatten/generated/FlattenOpSendTests.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/flatten/generated/FlattenOpSendTests.java
@@ -14,6 +14,6 @@ public final class FlattenOpSendTests extends FlattenClientTestBase {
     @Disabled
     public void testFlattenOpSendTests() {
         // method invocation
-        flattenClient.send("myRequiredId", null, "myRequiredInput", 0, 50, new User("myOptionalUser"));
+        flattenClient.send("myRequiredId", (String) null, "myRequiredInput", 0, 50, new User("myOptionalUser"));
     }
 }
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/model/generated/ModelOpPutNestedTests.java b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/model/generated/ModelOpPutNestedTests.java
index 7b090e408a7..d42dca08f84 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/model/generated/ModelOpPutNestedTests.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/model/generated/ModelOpPutNestedTests.java
@@ -17,7 +17,7 @@ public final class ModelOpPutNestedTests extends ModelClientTestBase {
     @Disabled
     public void testModelOpPutNestedTests() {
         // method invocation
-        NestedModel response = modelClient.putNested(null);
+        NestedModel response = modelClient.putNested((NestedModel) null);
 
         // response assertion
         Assertions.assertNotNull(response);
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/specialchars/generated/BuiltinOpReadTests.java b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/specialchars/generated/BuiltinOpReadTests.java
index 528efd7f53a..6d8c14ca7e9 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/specialchars/generated/BuiltinOpReadTests.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/specialchars/generated/BuiltinOpReadTests.java
@@ -15,7 +15,7 @@ public final class BuiltinOpReadTests extends SpecialCharsClientTestBase {
     @Disabled
     public void testBuiltinOpReadTests() {
         // method invocation
-        Resource response = specialCharsClient.read(null);
+        Resource response = specialCharsClient.read((String) null);
 
         // response assertion
         Assertions.assertNotNull(response);
diff --git a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/versioning/generated/VersioningOpListTests.java b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/versioning/generated/VersioningOpListTests.java
index a5a7574b420..71edf0fd3b4 100644
--- a/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/versioning/generated/VersioningOpListTests.java
+++ b/packages/http-client-java/generator/http-client-generator-test/src/test/java/tsptest/versioning/generated/VersioningOpListTests.java
@@ -17,7 +17,7 @@ public final class VersioningOpListTests extends VersioningClientTestBase {
     @Disabled
     public void testVersioningOpListTests() {
         // method invocation
-        PagedIterable<Resource> response = versioningClient.list(Arrays.asList("name=name"), null);
+        PagedIterable<Resource> response = versioningClient.list(Arrays.asList("name=name"), (String) null);
 
         // response assertion
         Assertions.assertEquals(200, response.iterableByPage().iterator().next().getStatusCode());