“Chad did an outstanding job in the last three days," Alouettes general manager Jim Popp said. "It was a total evaluation & he's a good fit. He's very happy and excited to be on the field again and we're happy to welcome him to the Alouettes."
Johnson, 36, caught 751 career passes for 10,783 yards and 66 touchdowns in the NFL with the Bengals.
He was traded to the New England Patriots in 2011 and caught only 15 passes and one touchdown.
Johnson signed with the Miami Dolphins in 2012, but was released after being arrested on domestic violence charges involving his former wife.
The Alouettes worked out Johnson at a minicamp in Vero Beach, Fla.
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Aaron Wilson covers the Ravens for The Baltimore Sun