The 23-year-old linebacker announced his retirement from the NFL this afternoon, Ravens general manager Ozzie Newsome said.
"Rolando let me know that he plans to retire from the NFL," Newsome said in a statement. "We have placed him on the reserve/retired list."
Baltimore had signed McClain to a one-year contract on April 12, hoping he could come closer to fulfilling his massive potential at middle linebacker. The Raiders selected him eighth overall in 2010 and he spent his first three professional seasons with Oakland before being cut loose this offseason.
He signed with the Ravens and was arrested for the third time since 2011 on April 21, this time for disorderly conduct and resisting arrest.
McClain recorded 274 tackles (195 solo), 6.5 sacks (for minus-42.5 yards), one interception, one forced fumble and 23 passes defensed in 41 career games with the Raiders.