Financial terms were not disclosed. The Cardinals hold an option for a fifth year on Johnson, the 17th overall selection.
"We're happy to have Bryant on board," Rod Graves, the team's Vice President for Football Operations, told the Arizona Republic. "Maybe life can get back to normalcy for a lot of us."
The deal with Johnson came a day after the Cardinals signed defensive end Calvin Pace, the 18th pick, to a similar pact.
Johnson was Penn State's go-to receiver in 2001, catching 51 passes for 866 yards and three touchdowns, including six for 149 yards against Miami.
Last season, the speedy wideout had 48 receptions for 917 yards and four scores, and also returned 41 punts for 528 yards.
Duggar sisters unveil Christian dating rules in new book
Astronomers offer more expansive view of universe