diff --git a/tools/cmake/run_size_tool.cmake b/tools/cmake/run_size_tool.cmake
index 0be2d369c4..707910254b 100644
--- a/tools/cmake/run_size_tool.cmake
+++ b/tools/cmake/run_size_tool.cmake
@@ -36,9 +36,6 @@ if(DEFINED ENV{SIZE_DIFF_FILE})
     list(APPEND IDF_SIZE_CMD "--diff=$ENV{SIZE_DIFF_FILE}")
 endif()
 
-if(DEFINED ENV{ESP_IDF_SIZE_NG})
-    list(APPEND IDF_SIZE_CMD "--unify")
-endif()
 
 list(APPEND IDF_SIZE_CMD ${MAP_FILE})
 
diff --git a/tools/idf_py_actions/core_ext.py b/tools/idf_py_actions/core_ext.py
index 3b9479fbac..b1d3d359bc 100644
--- a/tools/idf_py_actions/core_ext.py
+++ b/tools/idf_py_actions/core_ext.py
@@ -102,8 +102,6 @@ def action_extensions(base_actions: dict, project_path: str) -> Any:
 
         env: dict[str, Any] = {}
 
-        # Enforce NG mode for esp-idf-size v 1.x. After v 2.x is fully incorporated, 'ESP_IDF_SIZE_NG' can be removed.
-        env['ESP_IDF_SIZE_NG'] = '1'
         env['ESP_IDF_SIZE_FORCE_TERMINAL'] = '1'
         env['SIZE_OUTPUT_FORMAT'] = output_format
         if output_file:
diff --git a/tools/idf_size.py b/tools/idf_size.py
index 743ab98525..9d68005f3b 100755
--- a/tools/idf_size.py
+++ b/tools/idf_size.py
@@ -4,7 +4,6 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 #
-import os
 import subprocess
 import sys
 
@@ -12,8 +11,6 @@ if __name__ == '__main__':
     try:
         import esp_idf_size  # noqa: F401
 
-        # Enforce NG mode for esp-idf-size v 1.x. After v 2.x is fully incorporated, 'ESP_IDF_SIZE_NG' can be removed.
-        os.environ['ESP_IDF_SIZE_NG'] = '1'
     except ImportError:
         print('WARNING: esp-idf-size not installed, please run the install script to install it', file=sys.stderr)
         raise SystemExit(1)