He has a $1.05 million salary, the league minimum for players with seven-plus years of experience, and a $1.45 million signing bonus, a source told ESPN.
Whitehead, who turns 30 on April 2, adds veteran experience to a linebacker corps that lost Pro Bowler Luke Kuechly to retirement after the season.
Whitehead was a fifth-round pick by the Detroit Lions out of Temple in 2012, when new Panthers coach Matt Rhule was an assistant for the Owls. Rhule went on to become the head coach at Temple from 2013 to 2016.
The Raiders released Whitehead on March 9 in a move that cleared $6.25 million in salary-cap space.
Whitehead started all 32 games for the Raiders the past two seasons. He signed with the team as a free agent after six seasons with Detroit.
He had 108 combined tackles last season, the fourth straight year he had more than 100. However, his 941 defensive snaps last season were the most in the NFL for any linebacker who failed to record a sack, an interception, a fumble recovery or a forced fumble, according to research by The Associated Press.
After the Week 5 season-long suspension of middle linebacker Vontaze Burfict, Whitehead slid over from the strong side and assumed the role of defensive playcaller by wearing the green-dot helmet and playing in the middle of the Raiders' 4-3 base defense.
But late in the season, Whitehead was replaced at middle linebacker by Will Compton, who had been signed off the street.
ESPN's Paul Gutierrez contributed to this report.