The Cubs re-signed Thielbar to a one-year contract Tuesday, Jesse Rogers of ESPN.com reports.
Thielbar collected a 2.64 ERA and 56:13 K:BB over 58 regular-season innings for the Cubs in 2025. Left-handed batters hit just .161/.211/.276 off the southpaw. Thielbar -- who will turn 39 in January -- will help set up from the left side in the Cubs' bullpen.