diff --git a/onnxruntime/core/providers/webnn/builders/impl/conv_op_builder.cc b/onnxruntime/core/providers/webnn/builders/impl/conv_op_builder.cc
index 8c81b97e552e3..be2e4a042c826 100644
--- a/onnxruntime/core/providers/webnn/builders/impl/conv_op_builder.cc
+++ b/onnxruntime/core/providers/webnn/builders/impl/conv_op_builder.cc
@@ -69,7 +69,7 @@ common::Status SetConvBaseOptions(ModelBuilder& model_builder,
     std::vector<int64_t> dims;
     std::vector<int64_t> output_padding{0, 0};
     if (helper.HasAttr("output_shape")) {
-      // Default value of 'output_shape' will be ignore as we already check if it's existed.
+      // Default value of 'output_shape' will be ignored as we already check if it existed.
       dims = helper.Get("output_shape", std::vector<int64_t>{-1, -1});
       // Extract the height and width.
       std::vector<int64_t> output_shape;
@@ -77,10 +77,6 @@ common::Status SetConvBaseOptions(ModelBuilder& model_builder,
         output_shape = {dims[0], 1};
       } else if (dims.size() == 2 && !is_conv1d) {
         output_shape = dims;
-      } else if (dims.size() == 3 && is_conv1d) {  // ConvTranspose 1d
-        output_shape = {dims[2], 1};
-      } else if (dims.size() == 4 && !is_conv1d) {
-        output_shape = {dims[2], dims[3]};
       } else {
         return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "Invalid output shape");
       }
@@ -286,13 +282,9 @@ Status ConvOpBuilder::AddToModelBuilderImpl(ModelBuilder& model_builder, const N
     std::vector<uint32_t> new_shape = GetVecUint32FromVecInt64(input_shape);
     input = model_builder.GetBuilder().call<emscripten::val>("reshape", input, emscripten::val::array(new_shape));
 
-    weight_shape.push_back(1);
-    if (strides.size() == 1) {
-      strides.push_back(1);
-    }
-    if (dilations.size() == 1) {
-      dilations.push_back(1);
-    }
+    weight_shape.resize(4, 1);  // Ensure 4D by appending 1's if needed.
+    strides.resize(2, 1);  // Ensure 2D by appending 1's if needed.
+    dilations.resize(2, 1);  // Ensure 2D by appending 1's if needed.
     if (pads.size() == 2) {
       pads.insert(pads.begin() + 1, 0);
       pads.push_back(0);
@@ -314,7 +306,7 @@ Status ConvOpBuilder::AddToModelBuilderImpl(ModelBuilder& model_builder, const N
         options.set("filterLayout", emscripten::val("ihwo"));
       }
     }
-  } else { // ConvTranspose
+  } else {  // ConvTranspose
     if (is_nhwc) {
       options.set("inputLayout", emscripten::val("nhwc"));
       options.set("filterLayout", emscripten::val("ohwi"));