The deals ensure that all eight draft picks will be under contract when players report to training camp Sunday in Westminster.
"It's good to have each of our draft choices finished prior to the start of Brian (Billick)'s team meeting on Sunday," general manager Ozzie Newsome said.
Grubbs agreed to a five-year contract with a maximum value of $11 million if he reaches every incentive clause. His deal included $5.2 million in guaranteed money, the team said.
Grubbs, the 29th overall pick from Auburn, is slated to compete with Chris Chester for the starting right guard job.
He will be the first Ravens first-round draft pick to report on time since tight end Todd Heap in 2001.
McClain agreed to a three-year contract with minimum base salaries of $285,000 in 2007, $370,000 in 2008 and $460,000 in 2009. The former Alabama standout is competing with veteran Justin Green for the starting fullback job.