diff --git a/setup.cfg b/setup.cfg
index 88483b24..8376fb18 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -9,3 +9,11 @@ env=
 addopts =
     --verbose -n logical --durations=0 --durations-min=0.5
 testpaths = test/unit_tests
+filterwarnings =
+    # Many existing tests deliberately exercise the JaqcdProgram code path
+    # (e.g. parametrized tests that compare JAQCD vs OpenQASM behavior). The
+    # JAQCD deprecation warning is expected on those paths; ignore it here.
+    # Tests that specifically assert the warning fires use
+    # `pytest.warns(UserWarning, match="JaqcdProgram")` directly and are
+    # unaffected by this filter.
+    ignore:Submitting JaqcdProgram to LocalSimulator is deprecated:UserWarning
diff --git a/src/braket/default_simulator/simulator.py b/src/braket/default_simulator/simulator.py
index 9f2675e7..cc522cf1 100644
--- a/src/braket/default_simulator/simulator.py
+++ b/src/braket/default_simulator/simulator.py
@@ -138,6 +138,15 @@ def run(
         """
         Simulate a program using either OpenQASM or Jaqcd.
 
+        .. deprecated:: 1.39.4
+            Submitting a ``JaqcdProgram`` to a local simulator is deprecated
+            and emits a ``UserWarning``. Submit an ``OpenQASMProgram`` (or a
+            ``ProgramSet``) instead. Amazon Braket service devices no longer
+            accept JAQCD program submissions; see MCM-150287739. Local
+            simulators continue to accept JAQCD programs in this release so
+            historical notebooks keep working during the migration window;
+            JAQCD support will be removed in a future release.
+
         Args:
             circuit_ir (OpenQASMProgram | ProgramSet | JaqcdProgram): Program
                 specification.
@@ -161,6 +170,14 @@ def run(
             return self.run_openqasm(circuit_ir, *args, **kwargs)
         elif isinstance(circuit_ir, ProgramSet):
             return self.run_program_set(circuit_ir, *args, **kwargs)
+        if isinstance(circuit_ir, JaqcdProgram):
+            warnings.warn(
+                "Submitting JaqcdProgram to LocalSimulator is deprecated and "
+                "will be removed in a future release. Submit OpenQASMProgram "
+                "instead. Amazon Braket service devices no longer accept "
+                "JAQCD program submissions. See MCM-150287739.",
+                stacklevel=2,
+            )
         return self.run_jaqcd(circuit_ir, *args, **kwargs)
 
     def create_program_context(self) -> AbstractProgramContext:
diff --git a/test/unit_tests/braket/default_simulator/test_simulator.py b/test/unit_tests/braket/default_simulator/test_simulator.py
index 308f8a0b..70d1e187 100644
--- a/test/unit_tests/braket/default_simulator/test_simulator.py
+++ b/test/unit_tests/braket/default_simulator/test_simulator.py
@@ -11,12 +11,18 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 
+import json
+import warnings
+
 import numpy as np
 import pytest
+from braket.ir.jaqcd import Program as JaqcdProgram
+from braket.ir.openqasm import Program as OpenQASMProgram
 
 from braket.default_simulator import observables
 from braket.default_simulator.result_types import DensityMatrix, Expectation, Probability, Variance
 from braket.default_simulator.simulator import BaseLocalSimulator
+from braket.default_simulator.state_vector_simulator import StateVectorSimulator
 
 
 @pytest.mark.parametrize(
@@ -60,3 +66,50 @@ def test_observable_hash_tensor_product():
 def test_base_local_simulator_abstract():
     with pytest.raises(TypeError, match="Can't instantiate abstract class BaseLocalSimulator"):
         BaseLocalSimulator()
+
+
+def _minimal_jaqcd_program() -> JaqcdProgram:
+    """Build a minimal JaqcdProgram for warning-assertion tests."""
+    return JaqcdProgram.parse_raw(
+        json.dumps(
+            {
+                "instructions": [{"type": "h", "target": 0}],
+                "results": [{"type": "probability", "targets": [0]}],
+            }
+        )
+    )
+
+
+def _minimal_openqasm_program() -> OpenQASMProgram:
+    """Build a minimal OpenQASMProgram for warning-assertion tests."""
+    return OpenQASMProgram(
+        source="""
+        qubit q;
+        h q;
+        #pragma braket result probability q
+        """
+    )
+
+
+def test_run_jaqcd_emits_warning():
+    """Submitting a JaqcdProgram via BaseLocalSimulator.run should emit a
+    UserWarning telling the customer to migrate to OpenQASMProgram. The
+    program still executes — this is a soft deprecation."""
+    simulator = StateVectorSimulator()
+    with pytest.warns(UserWarning, match="JaqcdProgram"):
+        result = simulator.run(_minimal_jaqcd_program(), qubit_count=1, shots=10)
+    assert result is not None
+
+
+def test_run_openqasm_no_jaqcd_warning():
+    """The OpenQASM path must not emit the JAQCD deprecation warning. Assert
+    specifically on JAQCD-message warnings rather than erroring on all
+    UserWarnings, since other unrelated warnings (e.g. the density-matrix
+    noise advisory) are legitimate."""
+    simulator = StateVectorSimulator()
+    with warnings.catch_warnings(record=True) as w:
+        warnings.simplefilter("always")
+        result = simulator.run(_minimal_openqasm_program(), shots=10)
+    jaqcd_warnings = [x for x in w if "JaqcdProgram" in str(x.message)]
+    assert jaqcd_warnings == []
+    assert result is not None