diff --git a/backends/vulkan/cmake/ShaderLibrary.cmake b/backends/vulkan/cmake/ShaderLibrary.cmake
index a026660dd41..1a08dede41c 100644
--- a/backends/vulkan/cmake/ShaderLibrary.cmake
+++ b/backends/vulkan/cmake/ShaderLibrary.cmake
@@ -60,6 +60,14 @@ function(gen_vulkan_shader_lib_cpp shaders_path)
     )
   endif()
 
+  # Allow overriding GLSL PRECISION for fp16 shader variants. Empty / unset
+  # keeps upstream default (`highp`). Accepted values: highp, mediump, lowp.
+  if(EXECUTORCH_VULKAN_FP16_PRECISION)
+    list(APPEND GEN_SPV_ARGS "--fp16-precision"
+         "${EXECUTORCH_VULKAN_FP16_PRECISION}"
+    )
+  endif()
+
   # Ninja cannot expand wildcards (*) in DEPENDS lists.
   file(GLOB VULKAN_SHADERS "${shaders_path}/*.glsl" "${shaders_path}/*.glslh"
        "${shaders_path}/*.yaml" "${shaders_path}/*.h"
diff --git a/backends/vulkan/runtime/gen_vulkan_spv.py b/backends/vulkan/runtime/gen_vulkan_spv.py
index dab33fb3097..4d156e05433 100644
--- a/backends/vulkan/runtime/gen_vulkan_spv.py
+++ b/backends/vulkan/runtime/gen_vulkan_spv.py
@@ -663,6 +663,7 @@ def __init__(
         glslc_path: Optional[str],
         glslc_flags: str = "",
         replace_u16vecn: bool = False,
+        fp16_precision: str = "highp",
     ) -> None:
         if isinstance(src_dir_paths, str):
             self.src_dir_paths = [src_dir_paths]
@@ -678,6 +679,7 @@ def __init__(
         if "-Os" in self.glslc_flags_no_opt:
             self.glslc_flags_no_opt.remove("-Os")
         self.replace_u16vecn = replace_u16vecn
+        self.fp16_precision = fp16_precision
 
         self.src_files: Dict[str, str] = {}
         self.template_yaml_files: List[str] = []
@@ -857,6 +859,17 @@ def create_shader_params(
         for key, value in variant_params.items():
             shader_params[key] = value
 
+        # Optionally override PRECISION for half-precision variants. GLSL
+        # `mediump` is a hint the driver may use fp16 ALUs for arithmetic.
+        # On Mali GPUs it's typically honored; on Adreno it's typically
+        # ignored (harmless). Default is `highp` to match upstream behavior.
+        if (
+            self.fp16_precision != "highp"
+            and shader_params.get("DTYPE") == "half"
+            and shader_params.get("PRECISION") == "highp"
+        ):
+            shader_params["PRECISION"] = self.fp16_precision
+
         return shader_params
 
     def constructOutputMap(self) -> None:
@@ -1488,6 +1501,16 @@ def main(argv: List[str]) -> int:
         default=-1,
         help="Number of threads for shader compilation. -1 (default) uses all available CPU cores, 1 uses sequential compilation.",
     )
+    parser.add_argument(
+        "--fp16-precision",
+        choices=["highp", "mediump", "lowp"],
+        default="highp",
+        help=(
+            "GLSL PRECISION qualifier for DTYPE=half shader variants. "
+            "`mediump` lets drivers (notably Mali) use fp16 ALUs for arithmetic. "
+            "Default `highp` matches upstream behavior. Ignored on fp32 variants."
+        ),
+    )
     options = parser.parse_args()
 
     env = DEFAULT_ENV
@@ -1520,6 +1543,7 @@ def main(argv: List[str]) -> int:
         options.glslc_path,
         glslc_flags=glslc_flags_str,
         replace_u16vecn=options.replace_u16vecn,
+        fp16_precision=options.fp16_precision,
     )
     output_spv_files = shader_generator.generateSPV(
         options.output_path,
diff --git a/scripts/build_android_library.sh b/scripts/build_android_library.sh
index 0fb9e909884..1207b03827e 100755
--- a/scripts/build_android_library.sh
+++ b/scripts/build_android_library.sh
@@ -50,6 +50,7 @@ build_android_native_library() {
     -DEXECUTORCH_BUILD_QNN="${EXECUTORCH_BUILD_QNN}" \
     -DQNN_SDK_ROOT="${QNN_SDK_ROOT}" \
     -DEXECUTORCH_BUILD_VULKAN="${EXECUTORCH_BUILD_VULKAN}" \
+    -DEXECUTORCH_VULKAN_FP16_PRECISION="${EXECUTORCH_VULKAN_FP16_PRECISION:-highp}" \
     -DXNNPACK_ENABLE_ARM_SME2="${XNNPACK_ENABLE_ARM_SME2}" \
     -DSUPPORT_REGEX_LOOKAHEAD=ON \
     -DCMAKE_BUILD_TYPE="${EXECUTORCH_CMAKE_BUILD_TYPE}" \
diff --git a/tools/cmake/common/preset.cmake b/tools/cmake/common/preset.cmake
index 4ac45e28562..7d016db2347 100644
--- a/tools/cmake/common/preset.cmake
+++ b/tools/cmake/common/preset.cmake
@@ -82,12 +82,12 @@ macro(define_overridable_option NAME DESCRIPTION VALUE_TYPE DEFAULT_VALUE)
   if(DEFINED ${NAME} AND NOT DEFINED CACHE{${NAME}})
     set(${NAME}
         ${${NAME}}
-        CACHE ${VALUE_TYPE} ${DESCRIPTION} FORCE
+        CACHE ${VALUE_TYPE} "${DESCRIPTION}" FORCE
     )
   else()
     set(${NAME}
         ${DEFAULT_VALUE}
-        CACHE ${VALUE_TYPE} ${DESCRIPTION}
+        CACHE ${VALUE_TYPE} "${DESCRIPTION}"
     )
   endif()
 
diff --git a/tools/cmake/preset/default.cmake b/tools/cmake/preset/default.cmake
index 2c1be2dc9da..e48310b72e6 100644
--- a/tools/cmake/preset/default.cmake
+++ b/tools/cmake/preset/default.cmake
@@ -168,6 +168,12 @@ define_overridable_option(
 define_overridable_option(
   EXECUTORCH_BUILD_VULKAN "Build the Vulkan backend" BOOL OFF
 )
+define_overridable_option(
+  EXECUTORCH_VULKAN_FP16_PRECISION
+  "GLSL PRECISION for Vulkan half-precision shader variants. Accepted values: highp, mediump, lowp. `mediump` lets Mali drivers use fp16 ALUs; ignored on Adreno. Default `highp` matches upstream."
+  STRING
+  highp
+)
 define_overridable_option(
   EXECUTORCH_BUILD_WEBGPU "Build the WebGPU backend" BOOL OFF
 )