diff --git a/meta/lib/oe/spdx30_tasks.py b/meta/lib/oe/spdx30_tasks.py
index b6456a214a..dc82f21fb0 100644
--- a/meta/lib/oe/spdx30_tasks.py
+++ b/meta/lib/oe/spdx30_tasks.py
@@ -36,6 +36,24 @@ def set_timestamp_now(d, o, prop):
         delattr(o, prop)
 
 
+def get_release_date(d):
+    """Resolve the release date to record in a package's releaseTime property.
+
+    Uses SOURCE_DATE_EPOCH, which by this point (do_create_spdx runs after
+    do_unpack and do_deploy_source_date_epoch) reflects the source mtimes.
+    Omits the fallback value since it is not a meaningful release date.
+
+    Returns a datetime, or None if no release date should be recorded.
+    """
+    source_date_epoch = d.getVar("SOURCE_DATE_EPOCH")
+    if not source_date_epoch or source_date_epoch == d.getVar(
+        "SOURCE_DATE_EPOCH_FALLBACK"
+    ):
+        return None
+
+    return datetime.fromtimestamp(int(source_date_epoch), tz=timezone.utc)
+
+
 def add_license_expression(
     d, objset, license_expression, license_data, search_objsets=[]
 ):
@@ -441,6 +459,7 @@ def _enrich_source_package(d, dl, fd, file_name, primary_purpose):
 
 def add_download_files(d, objset):
     inputs = set()
+    release_date = get_release_date(d)
 
     urls = d.getVar("SRC_URI").split()
     fetch = bb.fetch.Fetch(urls, d)
@@ -504,6 +523,9 @@ def add_download_files(d, objset):
 
             _enrich_source_package(d, dl, fd, file_name, primary_purpose)
 
+            if release_date is not None:
+                dl.releaseTime = release_date
+
             if fd.method.supports_checksum(fd):
                 for checksum_id in bb.fetch.CHECKSUM_LIST:
                     if checksum_id not in oe.spdx30.HashAlgorithm.NAMED_INDIVIDUALS:
diff --git a/meta/lib/oeqa/selftest/cases/spdx.py b/meta/lib/oeqa/selftest/cases/spdx.py
index 8285189382..88c3eb6b15 100644
--- a/meta/lib/oeqa/selftest/cases/spdx.py
+++ b/meta/lib/oeqa/selftest/cases/spdx.py
@@ -6,6 +6,7 @@
 
 import textwrap
 import hashlib
+from datetime import datetime, timezone
 from oeqa.selftest.case import OESelftestTestCase
 from oeqa.utils.commands import bitbake, get_bb_var, get_bb_vars
 import oe.spdx30
@@ -443,3 +444,43 @@ class SPDX30Check(SPDX3CheckBase, OESelftestTestCase):
                 r'\d',
                 f"Version '{version}' for package '{name}' should contain digits"
             )
+
+    def test_release_date_source_date_epoch(self):
+        """releaseTime should be derived from SOURCE_DATE_EPOCH.
+
+        This is recorded on the downloaded source software_Package objects
+        produced by do_create_spdx (not the recipe-only do_create_recipe_spdx
+        task), since the release date can only be known once sources are
+        available and SOURCE_DATE_EPOCH has been computed.
+        """
+        # base-files has S == UNPACKDIR and never gets a real
+        # SOURCE_DATE_EPOCH, so use tar, which unpacks a real tarball.
+        objset = self.check_recipe_spdx(
+            "tar",
+            "{DEPLOY_DIR_SPDX}/{SSTATE_PKGARCH}/builds/build-tar.spdx.json",
+        )
+
+        source_date_epoch = get_bb_var("SOURCE_DATE_EPOCH", "tar")
+        expected = datetime.fromtimestamp(int(source_date_epoch), tz=timezone.utc)
+
+        pkg = None
+        for candidate in objset.foreach_type(oe.spdx30.software_Package):
+            if candidate.software_downloadLocation:
+                pkg = candidate
+                break
+
+        self.assertIsNotNone(pkg, "Unable to find downloaded source software_Package")
+        self.assertEqual(pkg.releaseTime, expected)
+
+    def test_release_date_omitted_without_downloaded_source(self):
+        """releaseTime only applies to downloaded source packages; recipes
+        with only local file:// sources have none, and get no releaseTime."""
+        # base-files only has file:// sources, so it has no downloaded
+        # source software_Package and thus no releaseTime anywhere.
+        objset = self.check_recipe_spdx(
+            "base-files",
+            "{DEPLOY_DIR_SPDX}/{MACHINE_ARCH}/builds/build-base-files.spdx.json",
+        )
+
+        for candidate in objset.foreach_type(oe.spdx30.software_Package):
+            self.assertIsNone(candidate.releaseTime)