diff --git a/pw_protobuf/docs.rst b/pw_protobuf/docs.rst
index 7ebfb14..2bbcda3 100644
--- a/pw_protobuf/docs.rst
+++ b/pw_protobuf/docs.rst
@@ -373,15 +373,15 @@
 
     while ((status = decoder.Next()).ok()) {
       switch (decoder.Field().value()) {
-        case Customer::Fields::AGE: {
+        case Customer::Fields::kAge: {
           PW_TRY_ASSIGN(age, decoder.ReadAge());
           break;
         }
-        case Customer::Fields::NAME: {
+        case Customer::Fields::kName: {
           PW_TRY(decoder.ReadName(name));
           break;
         }
-        case Customer::Fields::STATUS: {
+        case Customer::Fields::kStatus: {
           PW_TRY_ASSIGN(status, decoder.ReadStatus());
           break;
         }
@@ -391,6 +391,15 @@
     return status.IsOutOfRange() ? OkStatus() : status;
   }
 
+.. warning:: ``Fields::SNAKE_CASE`` is deprecated. Use ``Fields::kCamelCase``.
+
+  Transitional support for ``Fields::SNAKE_CASE`` will soon only be available by
+  explicitly setting the following GN variable in your project:
+  ``pw_protobuf_compiler_GENERATE_LEGACY_ENUM_SNAKE_CASE_NAMES=true``
+
+  This support will be removed after downstream projects have been migrated.
+
+
 Direct Writers and Readers
 ==========================
 The lowest level API is provided by the core C++ implementation, and requires
@@ -432,12 +441,12 @@
   #include "example_protos/customer.pwpb.h"
 
   Status EncodeCustomer(pw::protobuf::StreamEncoder& encoder) {
-    PW_TRY(encoder.WriteInt32(static_cast<uint32_t>(Customer::Fields::AGE),
+    PW_TRY(encoder.WriteInt32(static_cast<uint32_t>(Customer::Fields::kAge),
                               33));
-    PW_TRY(encoder.WriteString(static_cast<uint32_t>(Customer::Fields::NAME),
+    PW_TRY(encoder.WriteString(static_cast<uint32_t>(Customer::Fields::kName),
                                "Joe Bloggs"sv));
     PW_TRY(encoder.WriteUint32(
-        static_cast<uint32_t>(Customer::Fields::STATUS),
+        static_cast<uint32_t>(Customer::Fields::kStatus),
         static_cast<uint32_t>(Customer::Status::INACTIVE)));
   }
 
@@ -475,15 +484,15 @@
 
     while ((status = decoder.Next()).ok()) {
       switch (decoder.FieldNumber().value()) {
-        case static_cast<uint32_t>(Customer::Fields::AGE): {
+        case static_cast<uint32_t>(Customer::Fields::kAge): {
           PW_TRY_ASSIGN(age, decoder.ReadInt32());
           break;
         }
-        case static_cast<uint32_t>(Customer::Fields::NAME): {
+        case static_cast<uint32_t>(Customer::Fields::kName): {
           PW_TRY(decoder.ReadString(name));
           break;
         }
-        case static_cast<uint32_t>(Customer::Fields::STATUS): {
+        case static_cast<uint32_t>(Customer::Fields::kStatus): {
           uint32_t status_value;
           PW_TRY_ASSIGN(status_value, decoder.ReadUint32());
           status = static_cast<Customer::Status>(status_value);
@@ -1318,7 +1327,7 @@
 .. code:: c++
 
   my_proto_encoder.WriteAge(42);
-  my_proto_encoder.WriteInt32(static_cast<uint32_t>(MyProto::Fields::AGE), 42);
+  my_proto_encoder.WriteInt32(static_cast<uint32_t>(MyProto::Fields::kAge), 42);
 
 Repeated Fields
 ---------------
@@ -1371,7 +1380,7 @@
 
   my_proto_encoder.WriteNumbers(numbers);
   my_proto_encoder.WritePackedInt32(
-      static_cast<uint32_t>(MyProto::Fields::NUMBERS),
+      static_cast<uint32_t>(MyProto::Fields::kNumbers),
       numbers);
 
 Enumerations
@@ -1392,7 +1401,7 @@
 
   my_proto_encoder.WriteAward(MyProto::Award::SILVER);
   my_proto_encoder.WriteUint32(
-      static_cast<uint32_t>(MyProto::Fields::AWARD),
+      static_cast<uint32_t>(MyProto::Fields::kAward),
       static_cast<uint32_t>(MyProto::Award::SILVER));
 
 Repeated Fields
@@ -1530,11 +1539,11 @@
       // However, Field() is guaranteed to be valid after a call to Next()
       // that returns OK, so the value can be used directly here.
       switch (decoder.Field().value()) {
-        case MyProto::Fields::AGE: {
+        case MyProto::Fields::kAge: {
           PW_TRY_ASSIGN(age, decoder.ReadAge());
           break;
         }
-        case MyProto::Fields::NAME:
+        case MyProto::Fields::kName:
           // The string field is copied into the provided buffer. If the buffer
           // is too small to fit the string, RESOURCE_EXHAUSTED is returned and
           // the decoder is not advanced, allowing the field to be re-read.
@@ -1566,7 +1575,7 @@
 
     Store::Message store{};
     store.employees.SetDecoder([](Store::StreamDecoder& decoder) {
-      PW_ASSERT(decoder.Field().value() == Store::Fields::EMPLOYEES);
+      PW_ASSERT(decoder.Field().value() == Store::Fields::kEmployees);
 
       Employee::Message employee{};
       // Set any callbacks on `employee`.
@@ -1604,7 +1613,7 @@
 
 .. code:: c++
 
-  case Owner::Fields::PET: {
+  case Owner::Fields::kPet: {
     // Note that the parent decoder, owner_decoder, cannot be used until the
     // nested decoder, pet_decoder, has been destroyed.
     Animal::StreamDecoder pet_decoder = owner_decoder.GetPetDecoder();
@@ -1652,7 +1661,7 @@
 .. code:: c++
 
   PW_ASSERT(my_proto_decoder.FieldNumber().value() ==
-      static_cast<uint32_t>(MyProto::Fields::AGE));
+      static_cast<uint32_t>(MyProto::Fields::kAge));
   pw::Result<int32_t> my_proto_decoder.ReadInt32();
 
 Repeated Fields
@@ -1718,7 +1727,7 @@
   pw::Vector<int32_t, 8> numbers;
 
   PW_ASSERT(my_proto_decoder.FieldNumber().value() ==
-      static_cast<uint32_t>(MyProto::Fields::NUMBERS));
+      static_cast<uint32_t>(MyProto::Fields::kNumbers));
   my_proto_decoder.ReadRepeatedInt32(numbers);
 
 Enumerations
@@ -1758,7 +1767,7 @@
 .. code-block:: c++
 
   PW_ASSERT(my_proto_decoder.FieldNumber().value() ==
-      static_cast<uint32_t>(MyProto::Fields::AWARD));
+      static_cast<uint32_t>(MyProto::Fields::kAward));
   pw::Result<uint32_t> award_value = my_proto_decoder.ReadUint32();
   if (award_value.ok()) {
     MyProto::Award award = static_cast<MyProto::Award>(award_value);
diff --git a/pw_protobuf/py/pw_protobuf/codegen_pwpb.py b/pw_protobuf/py/pw_protobuf/codegen_pwpb.py
index 2a3346b..d5eadaa 100644
--- a/pw_protobuf/py/pw_protobuf/codegen_pwpb.py
+++ b/pw_protobuf/py/pw_protobuf/codegen_pwpb.py
@@ -256,7 +256,8 @@
         Result<{ctype}> ReadFoo({params...}) {
           Result<uint32_t> field_number = FieldNumber();
           PW_ASSERT(field_number.ok());
-          PW_ASSERT(field_number.value() == static_cast<uint32_t>(Fields::FOO));
+          PW_ASSERT(field_number.value() ==
+                    static_cast<uint32_t>(Fields::kFoo));
           return decoder_->Read{type}({params...});
         }
 
@@ -2315,7 +2316,10 @@
 
 
 def forward_declare(
-    node: ProtoMessage, root: ProtoNode, output: OutputFile
+    node: ProtoMessage,
+    root: ProtoNode,
+    output: OutputFile,
+    exclude_legacy_snake_case_field_name_enums: bool,
 ) -> None:
     """Generates code forward-declaring entities in a message's namespace."""
     namespace = node.cpp_namespace(root=root)
@@ -2327,6 +2331,14 @@
     with output.indent():
         for field in node.fields():
             output.write_line(f'{field.enum_name()} = {field.number()},')
+
+        # Migration support from SNAKE_CASE to kConstantCase.
+        if not exclude_legacy_snake_case_field_name_enums:
+            for field in node.fields():
+                output.write_line(
+                    f'{field.legacy_enum_name()} = {field.number()},'
+                )
+
     output.write_line('};')
 
     # Declare the message's message struct.
@@ -2551,6 +2563,7 @@
     package: ProtoNode,
     output: OutputFile,
     suppress_legacy_namespace: bool,
+    exclude_legacy_snake_case_field_name_enums: bool,
 ) -> None:
     """Generates code for a single .pb.h file corresponding to a .proto file."""
 
@@ -2593,7 +2606,12 @@
 
     for node in package:
         if node.type() == ProtoNode.Type.MESSAGE:
-            forward_declare(cast(ProtoMessage, node), package, output)
+            forward_declare(
+                cast(ProtoMessage, node),
+                package,
+                output,
+                exclude_legacy_snake_case_field_name_enums,
+            )
 
     # Define all top-level enums.
     for node in package.children():
@@ -2677,7 +2695,10 @@
 
 
 def process_proto_file(
-    proto_file, proto_options, suppress_legacy_namespace: bool
+    proto_file,
+    proto_options,
+    suppress_legacy_namespace: bool,
+    exclude_legacy_snake_case_field_name_enums: bool,
 ) -> Iterable[OutputFile]:
     """Generates code for a single .proto file."""
 
@@ -2690,7 +2711,11 @@
     output_filename = _proto_filename_to_generated_header(proto_file.name)
     output_file = OutputFile(output_filename)
     generate_code_for_package(
-        proto_file, package_root, output_file, suppress_legacy_namespace
+        proto_file,
+        package_root,
+        output_file,
+        suppress_legacy_namespace,
+        exclude_legacy_snake_case_field_name_enums,
     )
 
     return [output_file]
diff --git a/pw_protobuf/py/pw_protobuf/plugin.py b/pw_protobuf/py/pw_protobuf/plugin.py
index 9315b76..bc3c405 100755
--- a/pw_protobuf/py/pw_protobuf/plugin.py
+++ b/pw_protobuf/py/pw_protobuf/plugin.py
@@ -53,6 +53,12 @@
         help='If set, suppresses `using namespace` declarations, which '
         'disallows use of the legacy non-prefixed namespace',
     )
+    parser.add_argument(
+        '--exclude-legacy-snake-case-field-name-enums',
+        dest='exclude_legacy_snake_case_field_name_enums',
+        action='store_true',
+        help='Do not generate legacy SNAKE_CASE names for field name enums.',
+    )
 
     # protoc passes the custom arguments in shell quoted form, separated by
     # commas. Use shlex to split them, correctly handling quoted sections, with
@@ -87,6 +93,9 @@
             proto_file,
             proto_options,
             suppress_legacy_namespace=args.no_legacy_namespace,
+            exclude_legacy_snake_case_field_name_enums=(
+                args.exclude_legacy_snake_case_field_name_enums
+            ),
         )
         for output_file in output_files:
             fd = res.file.add()
diff --git a/pw_protobuf/py/pw_protobuf/proto_tree.py b/pw_protobuf/py/pw_protobuf/proto_tree.py
index 44c8804..15bfb73 100644
--- a/pw_protobuf/py/pw_protobuf/proto_tree.py
+++ b/pw_protobuf/py/pw_protobuf/proto_tree.py
@@ -505,6 +505,9 @@
         return self._field_name
 
     def enum_name(self) -> str:
+        return 'k' + self.name()
+
+    def legacy_enum_name(self) -> str:
         return self.upper_snake_case(
             symbol_name_mapping.fix_cc_enum_value_name(self._field_name)
         )
diff --git a/pw_protobuf_compiler/proto.gni b/pw_protobuf_compiler/proto.gni
index 8a69770..8a62801 100644
--- a/pw_protobuf_compiler/proto.gni
+++ b/pw_protobuf_compiler/proto.gni
@@ -85,17 +85,21 @@
         deps += invoker.other_deps
       }
 
-      args = [
-               "--language",
-               invoker.language,
-               "--include-file",
-               _includes[0],
-               "--compile-dir",
-               rebase_path(invoker.compile_dir, root_build_dir),
-               "--out-dir",
-               rebase_path(_out_dir, root_build_dir),
-               "--sources",
-             ] + rebase_path(invoker.sources, root_build_dir)
+      args = []
+      if (!pw_protobuf_compiler_GENERATE_LEGACY_ENUM_SNAKE_CASE_NAMES) {
+        args += [ "--exclude-pwpb-legacy-snake-case-field-name-enums" ]
+      }
+      args += [
+                "--language",
+                invoker.language,
+                "--include-file",
+                _includes[0],
+                "--compile-dir",
+                rebase_path(invoker.compile_dir, root_build_dir),
+                "--out-dir",
+                rebase_path(_out_dir, root_build_dir),
+                "--sources",
+              ] + rebase_path(invoker.sources, root_build_dir)
 
       if (defined(invoker.plugin)) {
         inputs = [ invoker.plugin ]
diff --git a/pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py b/pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py
index a87dcda..95e2605 100644
--- a/pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py
+++ b/pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py
@@ -81,6 +81,15 @@
         action='store_false',
         help='Do not generate pyi files for python',
     )
+    parser.add_argument(
+        '--exclude-pwpb-legacy-snake-case-field-name-enums',
+        dest='exclude_pwpb_legacy_snake_case_field_name_enums',
+        action='store_true',
+        help=(
+            'If set, generates legacy SNAKE_CASE names for field name enums '
+            'in PWPB.'
+        ),
+    )
 
     return parser
 
@@ -95,15 +104,27 @@
 def protoc_pwpb_args(
     args: argparse.Namespace, include_paths: List[str]
 ) -> Tuple[str, ...]:
-    return (
+    out_args = [
         '--plugin',
         f'protoc-gen-custom={args.plugin_path}',
         f'--custom_opt=-I{args.compile_dir}',
         *[f'--custom_opt=-I{include_path}' for include_path in include_paths],
-        '--custom_out',
-        args.out_dir,
+    ]
+
+    if args.exclude_pwpb_legacy_snake_case_field_name_enums:
+        out_args.append(
+            '--custom_opt=--exclude-legacy-snake-case-field-name-enums'
+        )
+
+    out_args.extend(
+        [
+            '--custom_out',
+            args.out_dir,
+        ]
     )
 
+    return tuple(out_args)
+
 
 def protoc_pwpb_rpc_args(
     args: argparse.Namespace, _include_paths: List[str]
diff --git a/pw_protobuf_compiler/toolchain.gni b/pw_protobuf_compiler/toolchain.gni
index 606e69d..806a963 100644
--- a/pw_protobuf_compiler/toolchain.gni
+++ b/pw_protobuf_compiler/toolchain.gni
@@ -20,4 +20,10 @@
   # in a single toolchain to avoid unnecessary duplication in the build.
   pw_protobuf_compiler_TOOLCHAIN =
       "$dir_pw_protobuf_compiler/toolchain:protocol_buffer"
+
+  # pwpb previously generated field enum names in SNAKE_CASE rather than
+  # kConstantCase. Set this variable to temporarily enable legacy SNAKE_CASE
+  # support while you migrate your codebase to kConstantCase.
+  # b/266298474
+  pw_protobuf_compiler_GENERATE_LEGACY_ENUM_SNAKE_CASE_NAMES = true
 }