The 6-1, 236-pounder was the first linebacker chosen this year after leading the Pac-10 in tackles last season at Oregon State with 121, and was the first drafted by the Packers in the first round since Wayne Simmons (Clemson) was selected with the 15th overall pick in 1993.
He had been barred from the first day of practice Saturday because he was unsigned.
His agent, Jack Scharf, told the Green Bay News-Chronicle that Barnett, the last of the Packers' nine picks this year, got seven years, but did not mention monetary figures. He also told the paper that the deal can be voided after five.
The paper also reported that Barnett watched the first day of practice from inside his vehicle across the street.
"That tells you right there what kind of player Green Bay is getting," Scharf said.