diff --git a/Lib/idlelib/pyshell.py b/Lib/idlelib/pyshell.py
index 6e57e306a3678d9..4965c14fd2a4ced 100755
--- a/Lib/idlelib/pyshell.py
+++ b/Lib/idlelib/pyshell.py
@@ -1674,6 +1674,10 @@ def main():
         if filename and os.path.isfile(filename):
             shell.interp.execfile(filename)
     if cmd or script:
+        # Let the startup file finish first: the command or script
+        # is to run after it, in its namespace (gh-68453).
+        while shell.executing:
+            root.update()
         shell.interp.runcommand("""if 1:
             import sys as _sys
             _sys.argv = {!r}
diff --git a/Misc/NEWS.d/next/IDLE/2026-09-15-21-20-04.gh-issue-68453.hlxbog.rst b/Misc/NEWS.d/next/IDLE/2026-09-15-21-20-04.gh-issue-68453.hlxbog.rst
new file mode 100644
index 000000000000000..4d8cfc1dbc6574a
--- /dev/null
+++ b/Misc/NEWS.d/next/IDLE/2026-09-15-21-20-04.gh-issue-68453.hlxbog.rst
@@ -0,0 +1,3 @@
+Fix running IDLE with the -s option together with -c, -r or -: the command
+or script now runs after the startup file, without an error dialog and
+without restarting the shell.