McClain is the third player drafted in the top 10 by late owner Al Davis to be let go so far this offseason by second-year general manager Reggie McKenzie. Defensive back Michael Huff (seventh pick in 2006) and receiver Darrius Heyward-Bey (seventh pick in '09) were cut last month.
Oakland has only two of its own first-round picks on the roster in running back Darren McFadden and kicker Sebastian Janikowski as McKenzie overhauls the roster. There are only 15 players left who were part of the organization at the end of the 2011 season.
"I'd like to thank the Raiders for giving me an opportunity to play in the NFL," McClain said in a statement Friday. "I'm disappointed that it hasn't worked out better, but I'm very excited and thankful for the Raiders allowing me to get a fresh start. I will miss my teammates and wish them and the Raiders organization good luck going forward.
McClain had a rough final campaign in Oakland, serving a two-game suspension last season for conduct detrimental to the team.
McClain was the eighth overall pick in the 2010 draft after helping Alabama win a national championship. He has struggled so far in his career and has had his playing time sharply reduced last season.
In 41 career games with Oakland, McClain had 6½ sacks, one interception, one forced fumble, no fumble recoveries and did little to help improve Oakland's struggling run defense.
After being essentially an every-down player for the first two years of his career, McClain was demoted after the first month of last season. He was replaced by rookie Miles Burris in nickel packages because of his struggles in pass coverage and because the coaching staff believed he tired too easily playing every down.
McClain also had problems off the field. He was involved in a shooting in Alabama in November 2011 when he left the team briefly during the season to attend a family funeral. McClain had been convicted of four misdemeanors in May but he appealed and the charges were dropped when the accuser told prosecutors he no longer wanted to pursue the case.
Information from The Associated Press was used in this report.