diff --git a/onnxruntime/core/providers/webnn/builders/impl/activation_op_builder.cc b/onnxruntime/core/providers/webnn/builders/impl/activation_op_builder.cc
index cb2ff135a7..c8aba274ad 100644
--- a/onnxruntime/core/providers/webnn/builders/impl/activation_op_builder.cc
+++ b/onnxruntime/core/providers/webnn/builders/impl/activation_op_builder.cc
@@ -17,10 +17,6 @@ class ActivationOpBuilder : public BaseOpBuilder {
  private:
   Status AddToModelBuilderImpl(ModelBuilder& model_builder, const Node& node,
                                const logging::Logger& logger) const override ORT_MUST_USE_RESULT;
-
-  // Operator support related.
- private:
-  int GetMinSupportedOpSet(const Node& node) const override;
 };
 
 // Add operator related.
@@ -70,13 +66,6 @@ Status ActivationOpBuilder::AddToModelBuilderImpl(ModelBuilder& model_builder,
   return Status::OK();
 }
 
-// Operator support related.
-
-int ActivationOpBuilder::GetMinSupportedOpSet(const Node& /* node */) const {
-  // Any operators < opset 6 used the deprecated "consumed_inputs attribute" which is unsupported.
-  return 6;
-}
-
 void CreateActivationOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations) {
   if (op_registrations.op_builder_map.find(op_type) != op_registrations.op_builder_map.cend())
     return;
diff --git a/onnxruntime/core/providers/webnn/builders/impl/base_op_builder.h b/onnxruntime/core/providers/webnn/builders/impl/base_op_builder.h
index 203e5b773c..601db0c1fc 100644
--- a/onnxruntime/core/providers/webnn/builders/impl/base_op_builder.h
+++ b/onnxruntime/core/providers/webnn/builders/impl/base_op_builder.h
@@ -39,7 +39,9 @@ class BaseOpBuilder : public IOpBuilder {
   virtual bool HasSupportedInputsImpl(const Node& node, const WebnnDeviceType device_type,
                                       const logging::Logger& logger) const;
 
-  virtual int GetMinSupportedOpSet(const Node& /* node */) const { return 1; }
+  // ONNX Runtime only *guarantees* support for models stamped
+  // with opset version 7 or above for opset domain 'ai.onnx'.
+  virtual int GetMinSupportedOpSet(const Node& /* node */) const { return 7; }
   virtual int GetMaxSupportedOpSet(const Node& /* node */) const { return 19; }
 
  private:
diff --git a/onnxruntime/core/providers/webnn/builders/impl/binary_op_builder.cc b/onnxruntime/core/providers/webnn/builders/impl/binary_op_builder.cc
index 8b45f0d16e..ac08f7a3f2 100644
--- a/onnxruntime/core/providers/webnn/builders/impl/binary_op_builder.cc
+++ b/onnxruntime/core/providers/webnn/builders/impl/binary_op_builder.cc
@@ -18,10 +18,6 @@ class BinaryOpBuilder : public BaseOpBuilder {
  private:
   Status AddToModelBuilderImpl(ModelBuilder& model_builder, const Node& node,
                                const logging::Logger& logger) const override ORT_MUST_USE_RESULT;
-
-  // Operator support related.
- private:
-  int GetMinSupportedOpSet(const Node& node) const override;
 };
 
 // Add operator related.
@@ -52,13 +48,6 @@ Status BinaryOpBuilder::AddToModelBuilderImpl(ModelBuilder& model_builder, const
   return Status::OK();
 }
 
-// Operator support related.
-
-int BinaryOpBuilder::GetMinSupportedOpSet(const Node& /* node */) const {
-  // Add/Sub/Mul/Div/Pow opset 6- has broadcast attributes we do not support now.
-  return 7;
-}
-
 void CreateBinaryOpBuilder(const std::string& op_type, OpBuilderRegistrations& op_registrations) {
   if (op_registrations.op_builder_map.find(op_type) != op_registrations.op_builder_map.cend())
     return;
diff --git a/onnxruntime/core/providers/webnn/builders/impl/cast_op_builder.cc b/onnxruntime/core/providers/webnn/builders/impl/cast_op_builder.cc
index 7c401dafd1..ed9cbbaaec 100644
--- a/onnxruntime/core/providers/webnn/builders/impl/cast_op_builder.cc
+++ b/onnxruntime/core/providers/webnn/builders/impl/cast_op_builder.cc
@@ -23,8 +23,6 @@ class CastOpBuilder : public BaseOpBuilder {
  private:
   bool IsOpSupportedImpl(const InitializedTensorSet& /* initializers */, const Node& node,
                          const WebnnDeviceType device_type, const logging::Logger& logger) const override;
-
-  int GetMinSupportedOpSet(const Node& node) const override;
 };
 
 // Add operator related.
@@ -76,11 +74,6 @@ Status CastOpBuilder::AddToModelBuilderImpl(ModelBuilder& model_builder,
 
 // Operator support related.
 
-int CastOpBuilder::GetMinSupportedOpSet(const Node& /* node */) const {
-  // Since opset 6, Cast uses attribute "to" as int type.
-  return 6;
-}
-
 bool CastOpBuilder::IsOpSupportedImpl(const InitializedTensorSet& /* initializers */,
                                       const Node& node,
                                       const WebnnDeviceType device_type,
diff --git a/onnxruntime/core/providers/webnn/builders/impl/reshape_op_builder.cc b/onnxruntime/core/providers/webnn/builders/impl/reshape_op_builder.cc
index 5d1db43653..b5005269b9 100644
--- a/onnxruntime/core/providers/webnn/builders/impl/reshape_op_builder.cc
+++ b/onnxruntime/core/providers/webnn/builders/impl/reshape_op_builder.cc
@@ -30,9 +30,6 @@ class ReshapeOpBuilder : public BaseOpBuilder {
  private:
   bool IsOpSupportedImpl(const InitializedTensorSet& initializers, const Node& node,
                          const WebnnDeviceType /* device_type */, const logging::Logger& logger) const override;
-
-  // Reshape opset 4- uses attributes for new shape which we do not support for now.
-  int GetMinSupportedOpSet(const Node& /* node */) const override { return 5; }
 };
 
 // Add operator related.