diff --git a/esphome/platformio/library.py b/esphome/platformio/library.py
index 306f07854e..ae0d86368a 100644
--- a/esphome/platformio/library.py
+++ b/esphome/platformio/library.py
@@ -577,6 +577,11 @@ def _make_registry_client() -> Any:
     """
     from platformio.package.manager._registry import PackageManagerRegistryMixin
 
+    from esphome.platformio.runner import patch_registry_private_packages
+
+    # Every lookup would otherwise sleep ~500 ms in PlatformIO's account probe
+    patch_registry_private_packages()
+
     class _Registry(PackageManagerRegistryMixin):
         def __init__(self) -> None:
             self._registry_client = None
diff --git a/esphome/platformio/runner.py b/esphome/platformio/runner.py
index 9bb2205a90..8107fd0e2b 100644
--- a/esphome/platformio/runner.py
+++ b/esphome/platformio/runner.py
@@ -2,7 +2,8 @@
 
 Invoked via ``python -m esphome.platformio.runner`` instead of
 ``python -m platformio`` so that the patches (incremental rebuild
-preservation, download retries) apply inside the subprocess. Running
+preservation, download retries, skipping the private-package probe) apply
+inside the subprocess. Running
 PlatformIO in a subprocess keeps its ``sys.path`` mutations and other
 global state from leaking into the ESPHome process.
 """
@@ -105,6 +106,28 @@ def patch_file_downloader() -> None:
     FileDownloader.__init__ = patched_init
 
 
+def patch_registry_private_packages() -> None:
+    """Answer PlatformIO's private-package probe without the network.
+
+    ``RegistryClient.get_package()`` calls ``allowed_private_packages()``
+    before it checks its own HTTP cache. That probe goes through
+    ``AccountClient``'s throttled ``send_request``, which sleeps up to 500 ms
+    to space out requests and then fails at once without a PlatformIO login,
+    so every registry lookup costs half a second of sleep for nothing.
+    ESPHome never uses private registry packages, so answer False directly.
+    """
+    from platformio.registry.client import RegistryClient
+
+    if getattr(RegistryClient.allowed_private_packages, "_esphome_patched", False):
+        return
+
+    def no_private_packages() -> bool:
+        return False
+
+    no_private_packages._esphome_patched = True  # type: ignore[attr-defined]  # pylint: disable=protected-access
+    RegistryClient.allowed_private_packages = staticmethod(no_private_packages)  # type: ignore[method-assign]
+
+
 _IGNORE_LIB_WARNINGS = "(?:Hash|Update)"
 # Regex patterns matched against each line of PlatformIO output. Lines that
 # match are dropped by RedirectText before they reach the parent process.
@@ -152,6 +175,7 @@ FILTER_PLATFORMIO_LINES = [
 def main() -> int:
     patch_structhash()
     patch_file_downloader()
+    patch_registry_private_packages()
 
     # Wrap stdout/stderr with RedirectText before PlatformIO runs:
     #
diff --git a/tests/unit_tests/test_platformio_library.py b/tests/unit_tests/test_platformio_library.py
index 0c873dc3fe..0928e30010 100644
--- a/tests/unit_tests/test_platformio_library.py
+++ b/tests/unit_tests/test_platformio_library.py
@@ -224,6 +224,28 @@ def test_resolve_registry_version_raises_without_pkg_file(monkeypatch):
         _resolve_registry_version("owner", "pkg", set())
 
 
+def test_make_registry_client_skips_private_package_probe(monkeypatch):
+    """Resolving through our client never sleeps in PlatformIO's account probe."""
+    from platformio.account.client import AccountClient
+    from platformio.registry.client import RegistryClient
+
+    # Undo the class-level patch after the test so other tests see the original
+    monkeypatch.setattr(
+        RegistryClient,
+        "allowed_private_packages",
+        RegistryClient.__dict__["allowed_private_packages"],
+    )
+
+    def fail(*_args, **_kwargs):
+        raise AssertionError("account probe must not run")
+
+    monkeypatch.setattr(AccountClient, "get_account_info", fail)
+
+    client = lib._make_registry_client().get_registry_client_instance()
+
+    assert client.allowed_private_packages() is False
+
+
 def _patch_registry_resolve(monkeypatch: pytest.MonkeyPatch) -> None:
     """Stub the registry lookup so tests never touch the network."""
     monkeypatch.setattr(
diff --git a/tests/unit_tests/test_platformio_runner.py b/tests/unit_tests/test_platformio_runner.py
index f375aa457a..ca59b8bee1 100644
--- a/tests/unit_tests/test_platformio_runner.py
+++ b/tests/unit_tests/test_platformio_runner.py
@@ -30,6 +30,7 @@ def _prepare_main(
     monkeypatch.setattr(sys, "stderr", stream)
     monkeypatch.setattr(runner, "patch_structhash", lambda: None)
     monkeypatch.setattr(runner, "patch_file_downloader", lambda: None)
+    monkeypatch.setattr(runner, "patch_registry_private_packages", lambda: None)
 
     platformio = ModuleType("platformio")
     platformio_main = ModuleType("platformio.__main__")
@@ -91,3 +92,62 @@ def test_main_still_filters_a_drained_partial_line(
 
     assert runner.main() == 0
     assert buf.getvalue() == b""
+
+
+def test_main_applies_registry_private_packages_patch(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """The probe patch is installed before PlatformIO gets control."""
+    order: list[str] = []
+    _prepare_main(monkeypatch, lambda: order.append("pio") or 0)
+    monkeypatch.setattr(
+        runner, "patch_registry_private_packages", lambda: order.append("patch")
+    )
+
+    assert runner.main() == 0
+    assert order == ["patch", "pio"]
+
+
+def _restore_registry_probe(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Undo the class-level patch after the test so other tests see PlatformIO's own probe."""
+    from platformio.registry.client import RegistryClient
+
+    monkeypatch.setattr(
+        RegistryClient,
+        "allowed_private_packages",
+        RegistryClient.__dict__["allowed_private_packages"],
+    )
+
+
+def test_patch_registry_private_packages_skips_account_probe(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """The patched probe answers False without touching the account client."""
+    from platformio.account.client import AccountClient
+    from platformio.registry.client import RegistryClient
+
+    _restore_registry_probe(monkeypatch)
+
+    def fail(*_args, **_kwargs):
+        raise AssertionError("account probe must not run")
+
+    monkeypatch.setattr(AccountClient, "get_account_info", fail)
+
+    runner.patch_registry_private_packages()
+
+    assert RegistryClient.allowed_private_packages() is False
+    assert RegistryClient().allowed_private_packages() is False
+
+
+def test_patch_registry_private_packages_is_idempotent(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    from platformio.registry.client import RegistryClient
+
+    _restore_registry_probe(monkeypatch)
+
+    runner.patch_registry_private_packages()
+    patched = RegistryClient.allowed_private_packages
+    runner.patch_registry_private_packages()
+
+    assert RegistryClient.allowed_private_packages is patched