He has struck a deal with the Lions on a four-year contract worth $16 million with $8 million guaranteed, according to the Detroit Free Press.
Pettigrew is expected to sign his contract today.
A former first-round draft pick from Oklahoma State, Pettigrew caught 41 passes for 416 yards and two touchdowns.
Pettigrew has 284 career catches for 2,828 yards and 16 touchdowns in five NFL seasons.
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Aaron Wilson covers the Ravens for The Baltimore Sun