diff --git a/backends/webgpu/test/op_tests/cases.py b/backends/webgpu/test/op_tests/cases.py
index d001b5857f4..1563fa7313c 100644
--- a/backends/webgpu/test/op_tests/cases.py
+++ b/backends/webgpu/test/op_tests/cases.py
@@ -719,3 +719,21 @@ def _relu_suite() -> WebGPUTestSuite:
         atol=1e-4,
         rtol=1e-3,
     )
+from executorch.backends.webgpu.test.ops.test_sub import (
+    CONFIGS as _SUB_CONFIGS,
+    SubModule,
+)
+
+
+@register_op_test("sub")
+def _sub_suite() -> WebGPUTestSuite:
+    # Full numeric coverage incl. the spatial broadcast + alpha (binary_sub.wgsl
+    # over a TensorMeta UBO); fp64 golden. Mirrors _mul_suite. alpha is a
+    # construct kwarg baked into the .pte, never a serialized input.
+    return WebGPUTestSuite(
+        module_factory=lambda alpha=1.0: SubModule(alpha),
+        cases=[
+            Case(name=name, construct={"alpha": alpha}, inputs=(sa, sb))
+            for name, (sa, sb, alpha) in _SUB_CONFIGS.items()
+        ],
+    )
diff --git a/backends/webgpu/test/ops/test_sub.py b/backends/webgpu/test/ops/test_sub.py
new file mode 100644
index 00000000000..24fc835e54a
--- /dev/null
+++ b/backends/webgpu/test/ops/test_sub.py
@@ -0,0 +1,71 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+"""`aten.sub.Tensor` (broadcast + alpha) module + configs for the WebGPU op-test framework.
+
+`SubModule` + `CONFIGS` are imported by `cases.py` to drive the declarative op-test
+suite (export via VulkanPartitioner + fp64 torch golden, run on Dawn). `SubTest` is
+the export-delegation smoke test. Configs span the same-shape fast path, the
+middle/spatial broadcast `[N,C,H,W] - [N,C,1,1]` (InstanceNorm `x - mean`), and an
+alpha != 1 case (`in1 - alpha * in2`).
+"""
+
+import unittest
+
+import torch
+
+from executorch.backends.vulkan.partitioner.vulkan_partitioner import VulkanPartitioner
+from executorch.exir import to_edge_transform_and_lower
+
+# name -> (shape_a, shape_b, alpha). Output shape is the broadcast of the two.
+CONFIGS = {
+    "same": ((8, 32), (8, 32), 1.0),  # fast path (same-shape)
+    "bcast_spatial": ((1, 8, 16, 16), (1, 8, 1, 1), 1.0),  # InstanceNorm x-mean [N,C,1,1]
+    "alpha": ((8, 32), (8, 32), 2.0),  # alpha != 1 (in1 - alpha * in2)
+}
+
+
+class SubModule(torch.nn.Module):
+    def __init__(self, alpha: float = 1.0) -> None:
+        super().__init__()
+        self.alpha = alpha
+
+    def forward(self, a: torch.Tensor, b: torch.Tensor) -> torch.Tensor:
+        return torch.sub(a, b, alpha=self.alpha)
+
+
+def _det_inputs(shape_a, shape_b):
+    """Deterministic fp32 inputs (fixed seed) for a config."""
+    g = torch.Generator().manual_seed(0)
+    a = torch.randn(*shape_a, generator=g, dtype=torch.float32)
+    b = torch.randn(*shape_b, generator=g, dtype=torch.float32)
+    return a, b
+
+
+def _export(a: torch.Tensor, b: torch.Tensor, alpha: float):
+    ep = torch.export.export(SubModule(alpha).eval(), (a, b))
+    return to_edge_transform_and_lower(
+        ep, partitioner=[VulkanPartitioner()]
+    ).to_executorch()
+
+
+def _delegated(et) -> bool:
+    return any(
+        d.id == "VulkanBackend"
+        for plan in et.executorch_program.execution_plan
+        for d in plan.delegates
+    )
+
+
+class SubTest(unittest.TestCase):
+    def test_export_delegates(self) -> None:
+        for name, (sa, sb, alpha) in CONFIGS.items():
+            with self.subTest(name=name):
+                a, b = _det_inputs(sa, sb)
+                et = _export(a, b, alpha)
+                self.assertTrue(
+                    _delegated(et), f"Expected a VulkanBackend delegate (sub {name})"
+                )