Ayanbadejo, 36, was due a $940,000 base salary this year, the second year of a three-year, $3.22 million contract that included a $400,000 signing bonus. The Ravens save roughly $807,000 against the salary cap by cutting the California native.
"We considered him one of the foundations of our team and he gave me sound counsel as one of our team leaders," Ravens coach John Harbaugh said of Ayanbadejo, who doubled as a reserve inside linebacker.
A three-time Pro Bowl selection, Ayanbadejo led the Ravens with 14 special-teams tackles last season. He had no special-teams tackles in the playoffs, though, as Baltimore allowed a pair of touchdown returns to Denver Broncos kick returner Trindon Holliday in the Ravens' AFC divisional round road victory.
"As a team, we place a high value on special teams and Brendon was one of our top performers in that area for the last five seasons," general manager Ozzie Newsome said in a statement. "The door may not be closed to bring him back to help us again.”
Ayanbadejo has 187 career special-teams tackles, leading or sharing the team lead in special-teams tackles seven times.
The former UCLA linebacker has previous stints with the Chicago Bears and Miami Dolphins as well as in the Canadian Football League with the Winnipeg Blue Bombers, Toronto Argonauts and the British Columbia Lions.
Ayanbadejo is one of the most socially active players in the NFL, an outspoken advocate of same-sex marriage, which was passed in Maryland in November.
"I would like to thank the city of Baltimore and the Ravens organization for an amazing ride," Ayanbadejo wrote on his official Twitter account Wednesday. "We will forever be united as champions!"