diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9729befa..e670f8da 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- SSL certificate verification failures in PyInstaller binary on systems without python.org Python installed; bundled `certifi` CA bundle is now auto-configured via runtime hook (#429)
 - Virtual package types (files, collections, subdirectories) now respect `ARTIFACTORY_ONLY=1`, matching the primary zip-archive proxy-only behavior (#418)
 - `apm pack --target claude` no longer produces an empty bundle when skills/agents are installed under `.github/` -- cross-target path mapping remaps `skills/` and `agents/` to the pack target prefix (#420)
 
diff --git a/build/apm.spec b/build/apm.spec
index bfaa75c5..36da3b01 100644
--- a/build/apm.spec
+++ b/build/apm.spec
@@ -122,6 +122,7 @@ hiddenimports = [
     'pathlib',
     'frontmatter',
     'requests',
+    'certifi',  # CA certificate bundle for SSL verification in frozen binary
     # Rich modules (lazily imported, must be explicitly included)
     'rich',
     'rich.console',
@@ -199,7 +200,7 @@ a = Analysis(
     hiddenimports=hiddenimports,
     hookspath=[],
     hooksconfig={},
-    runtime_hooks=[],
+    runtime_hooks=[str(repo_root / 'build' / 'hooks' / 'runtime_hook_ssl_certs.py')],
     excludes=excludes,
     win_no_prefer_redirects=False,
     win_private_assemblies=False,
diff --git a/build/hooks/runtime_hook_ssl_certs.py b/build/hooks/runtime_hook_ssl_certs.py
new file mode 100644
index 00000000..4b6462d2
--- /dev/null
+++ b/build/hooks/runtime_hook_ssl_certs.py
@@ -0,0 +1,40 @@
+# PyInstaller runtime hook -- configures SSL certificate paths for the
+# frozen binary so that HTTPS connections work on every platform without
+# requiring the user to install Python or set environment variables.
+#
+# Problem: PyInstaller bundles OpenSSL, but the compiled-in certificate
+# search path points at the *build machine's* Python framework directory
+# (e.g. /Library/Frameworks/Python.framework/...).  On end-user machines
+# that path rarely exists, causing SSL verification failures.
+#
+# Solution: Point ``SSL_CERT_FILE`` at the certifi CA bundle shipped
+# inside the frozen binary.  ``requests``, ``urllib3``, and the stdlib
+# ``ssl`` module all honour this variable.
+#
+# This hook executes before any application code so the variables are
+# visible to every subsequent import.
+
+import os
+import sys
+
+
+def _configure_ssl_certs() -> None:
+    """Set SSL_CERT_FILE to the bundled certifi CA bundle when frozen."""
+    if not getattr(sys, "frozen", False):
+        return
+
+    # Honour explicit user overrides -- never clobber them.
+    if os.environ.get("SSL_CERT_FILE") or os.environ.get("REQUESTS_CA_BUNDLE"):
+        return
+
+    try:
+        import certifi
+        ca_bundle = certifi.where()
+        if os.path.isfile(ca_bundle):
+            os.environ["SSL_CERT_FILE"] = ca_bundle
+    except Exception:
+        # certifi unavailable or broken -- fall through to system defaults.
+        pass
+
+
+_configure_ssl_certs()
diff --git a/tests/unit/test_ssl_cert_hook.py b/tests/unit/test_ssl_cert_hook.py
new file mode 100644
index 00000000..10b3a9d0
--- /dev/null
+++ b/tests/unit/test_ssl_cert_hook.py
@@ -0,0 +1,151 @@
+"""Tests for the PyInstaller SSL certificate runtime hook.
+
+The hook lives at ``build/hooks/runtime_hook_ssl_certs.py`` and is executed
+by PyInstaller before any application code.  These tests exercise the logic
+in isolation by importing the private helper directly.
+"""
+
+import importlib
+import os
+import sys
+from pathlib import Path
+from unittest.mock import patch, MagicMock
+
+import pytest
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+# The runtime hook is not inside a regular Python package, so we import it
+# manually from its file path.
+def _find_repo_root() -> Path:
+    """Walk up from this file until we find pyproject.toml (the repo root)."""
+    current = Path(__file__).resolve().parent
+    for parent in [current] + list(current.parents):
+        if (parent / "pyproject.toml").is_file():
+            return parent
+    raise RuntimeError("Cannot locate repository root (no pyproject.toml found)")
+
+
+_HOOK_PATH = _find_repo_root() / "build" / "hooks" / "runtime_hook_ssl_certs.py"
+
+
+def _load_hook_module():
+    """Import the runtime hook as a module.
+
+    Executes the module which defines ``_configure_ssl_certs`` *and* calls it
+    at module scope.  Tests invoke the function again with controlled env vars
+    to exercise each code path independently.
+    """
+    spec = importlib.util.spec_from_file_location("runtime_hook_ssl_certs", _HOOK_PATH)
+    mod = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(mod)
+    return mod
+
+
+def _get_configure_fn():
+    """Return a fresh reference to ``_configure_ssl_certs`` from the hook."""
+    mod = _load_hook_module()
+    return mod._configure_ssl_certs
+
+
+# ---------------------------------------------------------------------------
+# Tests
+# ---------------------------------------------------------------------------
+
+class TestSSLCertRuntimeHook:
+    """Tests for _configure_ssl_certs behaviour."""
+
+    def test_hook_file_exists(self):
+        """The runtime hook must exist at the expected path."""
+        assert _HOOK_PATH.is_file(), f"Missing runtime hook: {_HOOK_PATH}"
+
+    # -- Frozen-mode gating --------------------------------------------------
+
+    def test_noop_when_not_frozen(self, monkeypatch):
+        """When ``sys.frozen`` is absent, the hook must not set any env vars."""
+        monkeypatch.delattr(sys, "frozen", raising=False)
+        monkeypatch.delenv("SSL_CERT_FILE", raising=False)
+        monkeypatch.delenv("REQUESTS_CA_BUNDLE", raising=False)
+
+        fn = _get_configure_fn()
+        fn()
+
+        assert "SSL_CERT_FILE" not in os.environ
+
+    # -- User-override respect -----------------------------------------------
+
+    def test_respects_existing_ssl_cert_file(self, monkeypatch):
+        """If the user already set SSL_CERT_FILE, do not overwrite it."""
+        monkeypatch.setattr(sys, "frozen", True, raising=False)
+        monkeypatch.setenv("SSL_CERT_FILE", "/custom/ca.pem")
+        monkeypatch.delenv("REQUESTS_CA_BUNDLE", raising=False)
+
+        fn = _get_configure_fn()
+        fn()
+
+        assert os.environ["SSL_CERT_FILE"] == "/custom/ca.pem"
+
+    def test_respects_existing_requests_ca_bundle(self, monkeypatch):
+        """If the user already set REQUESTS_CA_BUNDLE, do not set SSL_CERT_FILE."""
+        monkeypatch.setattr(sys, "frozen", True, raising=False)
+        monkeypatch.delenv("SSL_CERT_FILE", raising=False)
+        monkeypatch.setenv("REQUESTS_CA_BUNDLE", "/custom/bundle.pem")
+
+        fn = _get_configure_fn()
+        fn()
+
+        assert "SSL_CERT_FILE" not in os.environ
+
+    # -- Happy path: frozen + certifi available ------------------------------
+
+    def test_sets_ssl_cert_file_when_frozen(self, monkeypatch, tmp_path):
+        """In a frozen binary with certifi, SSL_CERT_FILE is set automatically."""
+        ca_file = tmp_path / "cacert.pem"
+        ca_file.write_text("--- dummy CA bundle ---")
+
+        monkeypatch.setattr(sys, "frozen", True, raising=False)
+        monkeypatch.delenv("SSL_CERT_FILE", raising=False)
+        monkeypatch.delenv("REQUESTS_CA_BUNDLE", raising=False)
+
+        mock_certifi = MagicMock()
+        mock_certifi.where.return_value = str(ca_file)
+
+        with patch.dict("sys.modules", {"certifi": mock_certifi}):
+            fn = _get_configure_fn()
+            fn()
+
+        assert os.environ.get("SSL_CERT_FILE") == str(ca_file)
+
+    # -- Fallback: certifi missing -------------------------------------------
+
+    def test_graceful_when_certifi_missing(self, monkeypatch):
+        """If certifi is not importable, the hook silently continues."""
+        monkeypatch.setattr(sys, "frozen", True, raising=False)
+        monkeypatch.delenv("SSL_CERT_FILE", raising=False)
+        monkeypatch.delenv("REQUESTS_CA_BUNDLE", raising=False)
+
+        with patch.dict("sys.modules", {"certifi": None}):
+            fn = _get_configure_fn()
+            fn()  # must not raise
+
+        assert "SSL_CERT_FILE" not in os.environ
+
+    # -- Edge case: certifi points at missing file ---------------------------
+
+    def test_skips_when_ca_file_missing(self, monkeypatch, tmp_path):
+        """If certifi.where() returns a non-existent path, skip silently."""
+        monkeypatch.setattr(sys, "frozen", True, raising=False)
+        monkeypatch.delenv("SSL_CERT_FILE", raising=False)
+        monkeypatch.delenv("REQUESTS_CA_BUNDLE", raising=False)
+
+        mock_certifi = MagicMock()
+        mock_certifi.where.return_value = str(tmp_path / "does_not_exist.pem")
+
+        with patch.dict("sys.modules", {"certifi": mock_certifi}):
+            fn = _get_configure_fn()
+            fn()
+
+        assert "SSL_CERT_FILE" not in os.environ