The 5-foot-11, 203-pound safety from Alabama was the 95th selection overall.
Johnson understands how to play the game and is a potential first-year contributor as a nickel safety/special teams player. Get analysis on every pick from the draft. More ...
Johnson was an Alabama captain as a junior and senior. He was second on the team in tackles with 89, 60 solos, along with five interceptions, a sack, a forced fumble and a fumble recovery.
He was a unanimous all-SEC selection and was a second-team Associated Press all-American.
The signing announced Thursday leaves only first-round pick running back Beanie Wells and second-round pick linebacker Cody Brown without contract agreements among Cardinal draft picks.
In another move, Arizona released wide receiver Shane Morales, who had signed as an undrafted rookie free agent out of Oregon State on April 27.
The defending NFC champions report for training camp in Flagstaff on July 29.
Copyright 2009 by The Associated Press