diff --git a/cmake/onnxruntime_mlas.cmake b/cmake/onnxruntime_mlas.cmake
index 1a5eba9de4759..b8ab7142b6b35 100644
--- a/cmake/onnxruntime_mlas.cmake
+++ b/cmake/onnxruntime_mlas.cmake
@@ -796,11 +796,6 @@ else()
           ${MLAS_SRC_DIR}/intrinsics/avx2/qdwconv_avx2.cpp
           ${MLAS_SRC_DIR}/intrinsics/avx2/saturation_check_avx2.cpp
           ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx2.cpp
-          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit.h
-          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit.cpp
-          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit_blklen64.h
-          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit_blklen128.h
-          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit_blklen32.h
           ${MLAS_SRC_DIR}/sqnbitgemm_lut_kernel_avx2.h
           ${MLAS_SRC_DIR}/sqnbitgemm_lut_kernel_avx2.cpp
           ${MLAS_SRC_DIR}/rotary_embedding_kernel_avx2.h
@@ -847,9 +842,22 @@ endif()
           ${MLAS_SRC_DIR}/x86_64/QgemmU8X8KernelAvx512Core.S
           ${MLAS_SRC_DIR}/x86_64/ConvSymKernelAvx512Core.S
           ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512.cpp
+          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit.h
+          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit.cpp
+          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit_blklen64.h
+          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit_blklen128.h
+          ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit_blklen32.h
         )
         set_source_files_properties(${mlas_platform_srcs_avx512core} PROPERTIES COMPILE_FLAGS "-mfma -mavx512vnni -mavx512bw -mavx512dq -mavx512vl")
 
+        # Strip -mavx512vnni from the W2 scalar oracle / pack-helper TU so the
+        # compiler cannot autovectorize its int8 dot-product loops to vpdpbusd.
+        # Needed because this helper runs at model load on AVX-512-only
+        # (non-VNNI) hosts via the AVX-512 W2 dispatch. TU is pure C++ -- no
+        # AVX-512 intrinsics inside.
+        set_source_files_properties(${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512_2bit.cpp PROPERTIES
+          COMPILE_FLAGS "-mfma -mavx512bw -mavx512dq -mavx512vl")
+
         set(mlas_platform_srcs_avx512vnni
           ${MLAS_SRC_DIR}/sqnbitgemm_kernel_avx512vnni.cpp
           ${MLAS_SRC_DIR}/qkv_quant_kernel_avx512vnni.cpp
diff --git a/onnxruntime/test/mlas/unittest/test_sqnbitgemm_2bit_gemm.cpp b/onnxruntime/test/mlas/unittest/test_sqnbitgemm_2bit_gemm.cpp
index 7690b32c3c6a8..9e5a83d4fad99 100644
--- a/onnxruntime/test/mlas/unittest/test_sqnbitgemm_2bit_gemm.cpp
+++ b/onnxruntime/test/mlas/unittest/test_sqnbitgemm_2bit_gemm.cpp
@@ -310,6 +310,9 @@ void RunW2Case(size_t M, size_t N, size_t K, bool WithBias, uint32_t seed,
 // handler in a follow-up.
 //
 TEST(MlasSq2BitTest, Scalar_BlkLen64) {
+  if (!GetMlasPlatform().Avx512Supported_) {
+    GTEST_SKIP() << "AVX-512 not available on this host";
+  }
   struct Shape {
     size_t M, N, K;
   };
@@ -351,6 +354,9 @@ TEST(MlasSq2BitTest, Scalar_BlkLen64) {
 // Same coverage with per-block non-default zero points.
 //
 TEST(MlasSq2BitTest, Scalar_BlkLen64_WithZeroPoints) {
+  if (!GetMlasPlatform().Avx512Supported_) {
+    GTEST_SKIP() << "AVX-512 not available on this host";
+  }
   struct Shape {
     size_t M, N, K;
   };
@@ -806,6 +812,9 @@ constexpr struct {
 }  // namespace
 
 TEST(MlasSq2BitTest, Scalar_BlkLen128) {
+  if (!GetMlasPlatform().Avx512Supported_) {
+    GTEST_SKIP() << "AVX-512 not available on this host";
+  }
   for (uint32_t seed : {0xC0FFEEu, 0xBADC0DEu}) {
     for (const auto& s : kSimdShapes_BlkLen128) {
       for (bool bias : {false, true}) {
@@ -819,6 +828,9 @@ TEST(MlasSq2BitTest, Scalar_BlkLen128) {
 }
 
 TEST(MlasSq2BitTest, Scalar_BlkLen128_WithZeroPoints) {
+  if (!GetMlasPlatform().Avx512Supported_) {
+    GTEST_SKIP() << "AVX-512 not available on this host";
+  }
   for (uint32_t seed : {0xC0FFEEu, 0xBADC0DEu}) {
     for (const auto& s : kSimdShapes_BlkLen128) {
       for (bool bias : {false, true}) {
@@ -1160,6 +1172,9 @@ constexpr struct {
 }  // namespace
 
 TEST(MlasSq2BitTest, Scalar_BlkLen32) {
+  if (!GetMlasPlatform().Avx512Supported_) {
+    GTEST_SKIP() << "AVX-512 not available on this host";
+  }
   for (uint32_t seed : {0xC0FFEEu, 0xBADC0DEu}) {
     for (const auto& s : kSimdShapes_BlkLen32) {
       for (bool bias : {false, true}) {
@@ -1173,6 +1188,9 @@ TEST(MlasSq2BitTest, Scalar_BlkLen32) {
 }
 
 TEST(MlasSq2BitTest, Scalar_BlkLen32_WithZeroPoints) {
+  if (!GetMlasPlatform().Avx512Supported_) {
+    GTEST_SKIP() << "AVX-512 not available on this host";
+  }
   for (uint32_t seed : {0xC0FFEEu, 0xBADC0DEu}) {
     for (const auto& s : kSimdShapes_BlkLen32) {
       for (bool bias : {false, true}) {