Brendon played college football for the UCLA Bruins and was signed by the Atlanta Falcons as an undrafted free agent in 1999. 

Ayanbadejo has been selected to the Pro Bowl multiple times as a special teams player. He also was named to the All-Pro team several times as special teams player by Pro Football Weekly/Pro Football Writers Association. He has also been a member of the Chicago Bears and Miami Dolphins in the NFL, the Amsterdam Admirals in NFL Europe, and the Winnipeg Blue Bombers, Toronto Argonauts and BC Lions of the Canadian Football League (CFL). 

He helped the Ravens win Super Bowl XLVII in 2013.