diff --git a/esphome/platformio/extra_script.py b/esphome/platformio/extra_script.py
index d1550a680b..921fe2fd5d 100644
--- a/esphome/platformio/extra_script.py
+++ b/esphome/platformio/extra_script.py
@@ -13,6 +13,7 @@ from dataclasses import dataclass, field
 import logging
 import os
 from pathlib import Path
+import shlex
 from typing import TYPE_CHECKING
 
 from esphome.core import EsphomeError
@@ -259,8 +260,13 @@ def captured_as_build_flags(
         except ValueError:
             return str(resolved)
 
-    flags.extend(f"-I{_anchored(path)}" for path in _strs(result.cpppath, "CPPPATH"))
-    flags.extend(f"-L{_anchored(path)}" for path in _strs(result.libpath, "LIBPATH"))
+    # shlex.quote so a spaced path survives lex_build_flags as one token
+    flags.extend(
+        f"-I{shlex.quote(_anchored(path))}" for path in _strs(result.cpppath, "CPPPATH")
+    )
+    flags.extend(
+        f"-L{shlex.quote(_anchored(path))}" for path in _strs(result.libpath, "LIBPATH")
+    )
     flags.extend(f"-l{lib}" for lib in _strs(result.libs, "LIBS"))
     for define in result.cppdefines:
         # SCons also accepts dict/list CPPDEFINES; formatting those blind
diff --git a/tests/unit_tests/test_platformio_extra_script.py b/tests/unit_tests/test_platformio_extra_script.py
index dcb181caa3..9bff5dc892 100644
--- a/tests/unit_tests/test_platformio_extra_script.py
+++ b/tests/unit_tests/test_platformio_extra_script.py
@@ -329,6 +329,16 @@ def test_extra_script_cpppath_captured_as_include_flags(tmp_path, monkeypatch):
     assert flags == ["-Iinclude", f"-I{outside.resolve()}"]
 
 
+def test_extra_script_spaced_paths_survive_relexing(tmp_path):
+    """-I/-L paths with spaces round-trip through lex_build_flags as one token."""
+    from esphome.platformio.library import lex_build_flags
+
+    (tmp_path / "my libs").mkdir()
+    result = ExtraScriptResult(cpppath=["my libs"], libpath=["my libs"])
+    flags = captured_as_build_flags(result, library_dir=tmp_path)
+    assert lex_build_flags(flags, "test") == ["-Imy libs", "-Lmy libs"]
+
+
 def test_run_extra_script_failure_discards_partial_capture(tmp_path, caplog) -> None:
     """A crashed script yields an empty result: half-applied flags could
     build wrong-output firmware that links cleanly."""