The contract also includes a team option for a fifth year.
The 6-foot-4, 240-pound Louisiana State product was the No. 6 overall pick in the 2013 NFL Draft.
Mingo played in 40 games for LSU between 2010-12, recording 119 tackles, 15 sacks, four forced fumbles and three fumble recoveries.
The Browns have now signed all of their draft picks.
Copyright 2013 ABC News Radio
James Hanlon, CNN
Emanuella Grinberg, CNN
Adam Forsgren, EastIdahoNews.com Columnist