Haynes agreed to a six-year deal while Grossman, the fourth quarterback selected overall, signed a five-year contract.
Financial terms were not disclosed.
Haynes, the 14th overall pick, led the Big Ten with 15 sacks, and also had 80 tackles, including 23 for losses, and seven forced fumbles last season.
Grossman is not expected to play immediately, but has been designated as the Bears' "quarterback of the future." He starts training camp as third string behind Kordell Stewart, who signed a two-year contract in the offseason, and veteran Chris Chandler.
He threw for 3,402 yards and 22 touchdowns with 17 interceptions last season, and ranks second in school history in completion percentage (61 percent) and touchdowns (77).