diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index ed724e55a..ecf8fb1d1 100755
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,6 +1,15 @@
 Model Optimizer Changelog (Linux)
 =================================
 
+0.39 (2025-10-xx)
+^^^^^^^^^^^^^^^^^
+
+**Deprecations**
+
+**New Features**
+
+- Add flag ``op_types_to_exclude_fp16`` in ONNX quantization to exclude ops from being converted to FP16/BF16. Alternatively, for custom TensorRT ops, this can also be done by indicating ``'fp32'`` precision in ``trt_plugins_precision``.
+
 0.37 (2025-09-xx)
 ^^^^^^^^^^^^^^^^^
 
diff --git a/modelopt/onnx/quantization/__main__.py b/modelopt/onnx/quantization/__main__.py
index 1be2e75df..55cca6ee5 100644
--- a/modelopt/onnx/quantization/__main__.py
+++ b/modelopt/onnx/quantization/__main__.py
@@ -90,28 +90,33 @@ def get_parser() -> argparse.ArgumentParser:
     argparser.add_argument(
         "--op_types_to_quantize",
         type=str,
-        default=[],
         nargs="+",
         help="A space-separated list of node types to quantize.",
     )
     argparser.add_argument(
         "--op_types_to_exclude",
         type=str,
-        default=[],
         nargs="+",
         help="A space-separated list of node types to exclude from quantization.",
     )
+    argparser.add_argument(
+        "--op_types_to_exclude_fp16",
+        type=str,
+        nargs="+",
+        help=(
+            "A space-separated list of node types to exclude from FP16/BF16 conversion. "
+            "Relevant when --high_precision_dtype is 'fp16' or 'bf16'."
+        ),
+    )
     argparser.add_argument(
         "--nodes_to_quantize",
         type=str,
-        default=[],
         nargs="+",
         help="A space-separated list of node names to quantize. Regular expressions are supported.",
     )
     argparser.add_argument(
         "--nodes_to_exclude",
         type=str,
-        default=[],
         nargs="+",
         help="A space-separated list of node names to exclude from quantization. Regular expressions are supported.",
     )
@@ -274,6 +279,7 @@ def main():
         override_shapes=args.override_shapes,
         op_types_to_quantize=args.op_types_to_quantize,
         op_types_to_exclude=args.op_types_to_exclude,
+        op_types_to_exclude_fp16=args.op_types_to_exclude_fp16,
         nodes_to_quantize=args.nodes_to_quantize,
         nodes_to_exclude=args.nodes_to_exclude,
         use_external_data_format=args.use_external_data_format,
diff --git a/modelopt/onnx/quantization/fp8.py b/modelopt/onnx/quantization/fp8.py
index 4ee9c4f67..1ef3c9799 100755
--- a/modelopt/onnx/quantization/fp8.py
+++ b/modelopt/onnx/quantization/fp8.py
@@ -168,6 +168,7 @@ def quantize(
     calibration_eps: list[str] = ["cpu", "cuda:0", "trt"],
     op_types_to_quantize: list[str] | None = None,
     op_types_to_exclude: list[str] | None = None,
+    op_types_to_exclude_fp16: list[str] | None = None,
     nodes_to_quantize: list[str] | None = None,
     nodes_to_exclude: list[str] | None = None,
     use_external_data_format: bool = False,
@@ -318,7 +319,7 @@ def quantize(
         onnx_model = convert_to_f16(
             onnx_model,
             keep_io_types=not direct_io_types,
-            op_block_list=["Resize"],
+            op_block_list=op_types_to_exclude_fp16 or [],
             low_precision_type=high_precision_dtype,
             trt_plugins=trt_extra_plugin_lib_paths,
         )
diff --git a/modelopt/onnx/quantization/int8.py b/modelopt/onnx/quantization/int8.py
index 156e798b0..5a878fb76 100755
--- a/modelopt/onnx/quantization/int8.py
+++ b/modelopt/onnx/quantization/int8.py
@@ -119,6 +119,7 @@ def quantize(
     calibration_eps: list[str] = ["cpu", "cuda:0", "trt"],
     op_types_to_quantize: list[str] | None = None,
     op_types_to_exclude: list[str] | None = None,
+    op_types_to_exclude_fp16: list[str] | None = None,
     nodes_to_quantize: list[str] | None = None,
     nodes_to_exclude: list[str] | None = None,
     use_external_data_format: bool = False,
@@ -279,6 +280,7 @@ def quantize(
         onnx_model = convert_to_f16(
             onnx_model,
             keep_io_types=not direct_io_types,
+            op_block_list=op_types_to_exclude_fp16 or [],
             low_precision_type=high_precision_dtype,
             trt_plugins=trt_extra_plugin_lib_paths,
         )
diff --git a/modelopt/onnx/quantization/quantize.py b/modelopt/onnx/quantization/quantize.py
index 9f6f9cae9..daf785326 100755
--- a/modelopt/onnx/quantization/quantize.py
+++ b/modelopt/onnx/quantization/quantize.py
@@ -81,7 +81,7 @@ def _preprocess_onnx(
     override_shapes: str,
     simplify: bool = False,
     quantize_mode: str = "int8",
-) -> tuple[str, onnx.ModelProto, list[str], bool, bool, bool, dict]:
+) -> tuple[str, onnx.ModelProto, list[str], bool, bool, bool, dict, dict]:
     logger.info(f"Preprocessing the model {onnx_path}")
     intermediate_generated_files = []
     output_dir = os.path.dirname(output_path)
@@ -180,13 +180,14 @@ def _preprocess_onnx(
         intermediate_generated_files.append(onnx_path)
 
     # If custom op precisions are given, add Cast or Q/DQ where appropriate.
+    custom_ops_to_cast = {}
     custom_ops_to_quantize = {}
     if trt_plugins_precision:
         custom_ops_to_cast, custom_ops_to_quantize = interpret_trt_plugins_precision_flag(
             onnx_model, trt_plugins_precision, quantize_mode
         )
-        if custom_ops_to_cast:
-            onnx_model = cast_custom_ops(onnx_model, custom_ops_to_cast)
+        if custom_ops_to_cast.get("fp16", {}):
+            onnx_model = cast_custom_ops(onnx_model, custom_ops_to_cast["fp16"])
             onnx_path = os.path.join(output_dir, f"{model_name}_castFP16.onnx")
             save_onnx(onnx_model, onnx_path, use_external_data_format)
             logger.info(f"Model is cloned to {onnx_path} after casting tensors to FP16")
@@ -199,6 +200,7 @@ def _preprocess_onnx(
         has_custom_op,
         has_dds_op,
         use_external_data_format,
+        custom_ops_to_cast.get("fp32", {}),
         custom_ops_to_quantize,
     )
 
@@ -214,6 +216,7 @@ def quantize(
     override_shapes: str | None = None,
     op_types_to_quantize: list[str] | None = None,
     op_types_to_exclude: list[str] | None = None,
+    op_types_to_exclude_fp16: list[str] | None = None,
     nodes_to_quantize: list[str] | None = None,
     nodes_to_exclude: list[str] | None = None,
     use_external_data_format: bool = False,
@@ -265,6 +268,9 @@ def quantize(
             This flag does not support regular expression.
         op_types_to_exclude:
             List of op types to exclude from quantization. This flag does not support regular expression.
+        op_types_to_exclude_fp16:
+            List of op types to exclude from FP16 conversion.
+            This is only relevant if '--high_precision_dtype != fp32'.
         nodes_to_quantize:
             List of node names to quantize. If None (default), all supported nodes are quantized.
             This flag supports regular expression.
@@ -406,6 +412,7 @@ def quantize(
         has_custom_op,
         has_dds_op,
         use_external_data_format,
+        custom_ops_to_cast_fp32,
         custom_ops_to_quantize,
     ) = _preprocess_onnx(
         onnx_path,
@@ -420,6 +427,16 @@ def quantize(
     )
     trt_plugins = update_trt_ep_support(calibration_eps, has_dds_op, has_custom_op, trt_plugins)  # type: ignore[arg-type]
 
+    # Update list with op types to exclude from FP16/BF16 conversion
+    op_types_to_exclude_fp16 = list(
+        dict.fromkeys((op_types_to_exclude_fp16 or []) + list(custom_ops_to_cast_fp32.keys()))
+    )
+    if high_precision_dtype == "fp32" and op_types_to_exclude_fp16:
+        logger.warning(
+            "Nodes were detected for exclusion from FP16/BF16 conversion, but 'high_precision_dtype' is set to FP32. "
+            "Since the model won't be converted to a lower precision, this flag is void."
+        )
+
     # Use random scales if calibration data is not supplied
     if calibration_data is None:
         calibration_data_reader = RandomDataProvider(onnx_path, calibration_shapes)
@@ -461,6 +478,7 @@ def quantize(
             calibration_eps=calibration_eps,
             op_types_to_quantize=op_types_to_quantize,
             op_types_to_exclude=op_types_to_exclude,
+            op_types_to_exclude_fp16=op_types_to_exclude_fp16,
             nodes_to_quantize=nodes_to_quantize,
             nodes_to_exclude=nodes_to_exclude,
             use_external_data_format=use_external_data_format,
diff --git a/modelopt/onnx/trt_utils.py b/modelopt/onnx/trt_utils.py
index 85312ecd4..2231ccd00 100644
--- a/modelopt/onnx/trt_utils.py
+++ b/modelopt/onnx/trt_utils.py
@@ -367,10 +367,12 @@ def interpret_trt_plugins_precision_flag(
         if trt_plugin_precision.count(":") == 1:
             if precision not in supported_precisions:
                 logger.warning(f"Precision {precision} is not supported. Skipping.")
-            if precision == "fp16":
-                custom_ops_to_cast[op_type] = {
-                    "inp": list(range(num_inps)),
-                    "out": list(range(num_outs)),
+            if precision in ["fp16", "fp32"]:
+                custom_ops_to_cast[precision] = {
+                    op_type: {
+                        "inp": list(range(num_inps)),
+                        "out": list(range(num_outs)),
+                    }
                 }
             if precision in ["int8", "fp8"]:
                 if precision != quantize_mode:
@@ -408,10 +410,14 @@ def interpret_trt_plugins_precision_flag(
                     f"Setting the custom op precision to be the same as quantize mode."
                 )
 
-            # Will cast the inputs to FP16 and the outputs back to FP32
-            inp_precision_cast = [i for i, p in enumerate(inp_precision) if p == "fp16"]
-            out_precision_cast = [i for i, p in enumerate(out_precision) if p in ["fp16", "fp32"]]
-            custom_ops_to_cast[op_type] = {"inp": inp_precision_cast, "out": out_precision_cast}
+            # Will cast the inputs to FP16/FP32 and the outputs back to FP32
+            for precision in ["fp16", "fp32"]:
+                inp_precision_cast = [i for i, p in enumerate(inp_precision) if p == precision]
+                out_precision_cast = [i for i, p in enumerate(out_precision) if p == precision]
+                if inp_precision_cast:
+                    custom_ops_to_cast[precision] = {
+                        op_type: {"inp": inp_precision_cast, "out": out_precision_cast}
+                    }
 
             # Will add Q/DQ nodes in the requested I/O indices
             inp_precision_quant = [i for i, p in enumerate(inp_precision) if p in ["int8", "fp8"]]