The Lions, who drafted Suh to boost their porous defense, did not release terms of the deal, but local media reported Suh received a five-year contract worth $68 million with $40 million guaranteed.
Suh, who missed four days of training camp, was expected to practice with the Lions on Wednesday, the team reported on its website (www.detroitlions.com).
His signing leaves offensive tackle Russell Okung (Seattle) and running back C.J. Spiller (Buffalo) as the only top 10 picks from April's draft without contracts.
The top choice, quarterback Sam Bradford, agreed to a six-year, $78 million deal with the St. Louis Rams last week. It includes $50 million guaranteed.
(Reporting by Gene Cherry in Raleigh, North Carolina; Editing by Frank Pingue)