He was drafted by the Rams in the seventh round of the 2008 NFL Draft on April 27, 2008. On July 20, 2008, Chamberlain signed a three-year $1.186 million contract with the Rams. Chamberlain led the Rams in special teams tackles in 2008 with 19. In 2009 Chamberlain was a backup outside linebacker who made one start and led the team in special teams tackles (28) for the second consecutive season. He made 13 starts during the 2011 Regular Season and made a career-high 80 tackles. Chamberlain signed with the New Orleans Saints on March 23, 2012. After tearing his anterior cruciate ligament (ACL), he was placed on injured reserve on August 19, 2012. Attempting a comeback in 2013, he was again placed on injured reserve on August 27, 2013. On September 3, 2013, the Saints released Chamberlain, using a "failure to disclose" designation that indicated Chamberlain had an undisclosed physical condition, so that the Saints would not be responsible for remaining financial obligations to Chamberlain. Chamberlain's agent said he disagreed with this designation and would file a grievance to have the matter resolved.