Lewis, 22, started 45 games for the Cowboys and last year made 73 tackles, eight for losses, and had half a sack along with three interceptions and two forced fumbles.
Lewis made the coaches All-Big 12 team and the second team Associated Press All-Big 12 squad, as well as earning Academic All-Big 12 honors his final two seasons.
In his career at Oklahoma State, Lewis had eight interceptions, seven forced fumbles and scored a pair of defensive touchdowns.
At 5-foot-11 and 225 pounds, Lewis played outside linebacker at Oklahoma State and became a starter midway through his freshman season in 2010.
With the addition of Lewis, 27 of the Packers’ 90 training camp roster spots (30 percent) are occupied by rookies, with 18 of those rookies coming after the draft as undrafted free agents.
Lewis projects as an inside linebacker for the Packers and he may also be asked to play on special teams.