diff --git a/CHANGELOG.md b/CHANGELOG.md
index a9118e3..230243e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,13 +7,11 @@ and this project follows [Semantic Versioning](https://semver.org/spec/v2.0.0.ht
 
 ## [Unreleased]
 
-### Added
-- Added `python -m devr.release_preflight` to run release artifact smoke tests and validate changelog/version consistency before tagging.
-
 ## [0.1.0] - 2026-02-17
 
 ### Added
 - Added `devr doctor` for environment diagnostics and setup troubleshooting.
+- Added `python -m devr.release_preflight` to run release artifact smoke tests and validate changelog/version consistency before tagging.
 
 ### Changed
 - Improved `devr check` diagnostics with explicit stage headers and command summaries.
diff --git a/src/devr/release_preflight.py b/src/devr/release_preflight.py
index a8add12..78eb8e9 100644
--- a/src/devr/release_preflight.py
+++ b/src/devr/release_preflight.py
@@ -46,6 +46,7 @@ def changelog_versions(changelog_path: Path) -> list[str]:
 
 def validate_changelog(changelog_path: Path, version: str) -> None:
     """Validate changelog has expected release structure for ``version``."""
+    changelog_text = changelog_path.read_text(encoding="utf-8")
     versions = changelog_versions(changelog_path)
     if not versions or versions[0] != "Unreleased":
         raise ReleasePreflightError(
@@ -57,6 +58,17 @@ def validate_changelog(changelog_path: Path, version: str) -> None:
             "Move completed entries from Unreleased into that release section before tagging."
         )
 
+    unreleased_match = re.search(
+        r"^## \[Unreleased\]\s*(.*?)(?=^## \[|\Z)",
+        changelog_text,
+        flags=re.MULTILINE | re.DOTALL,
+    )
+    if unreleased_match and unreleased_match.group(1).strip():
+        raise ReleasePreflightError(
+            "CHANGELOG.md has unreleased entries. Move completed entries from "
+            "'Unreleased' into the current version section before tagging."
+        )
+
 
 def run_checked(cmd: list[str], cwd: Path) -> None:
     """Run command and fail with a clear message on non-zero exit."""
diff --git a/tests/test_release_preflight.py b/tests/test_release_preflight.py
index 00f3742..1fab810 100644
--- a/tests/test_release_preflight.py
+++ b/tests/test_release_preflight.py
@@ -35,6 +35,17 @@ def test_validate_changelog_requires_current_version_section(tmp_path: Path) ->
         validate_changelog(changelog, "0.1.0")
 
 
+def test_validate_changelog_requires_empty_unreleased_section(tmp_path: Path) -> None:
+    changelog = tmp_path / "CHANGELOG.md"
+    changelog.write_text(
+        "## [Unreleased]\n\n### Added\n- pending item\n\n## [0.1.0] - 2026-01-01\n",
+        encoding="utf-8",
+    )
+
+    with pytest.raises(ReleasePreflightError, match="unreleased entries"):
+        validate_changelog(changelog, "0.1.0")
+
+
 def test_changelog_versions_extracts_headings(tmp_path: Path) -> None:
     changelog = tmp_path / "CHANGELOG.md"
     changelog.write_text(