Samardzija was projected to be a mid-to-late first-round pick in April's NFL Draft but instead of waiting to hear which football team selected him, he'll be at baseball spring training in Arizona.
The Cubs announced the signing Friday.
Chicago drafted Samardzija in the fifth round of the 2006 draft. Over 50 pitching appearances for the Fighting Irish, he was 21-6 with a 3.82 earned run average.
On the football field, Samardzija set Notre Dame records for receiving yards (2,593) and receiving touchdowns (27).