Isaac Chamberlain (born 3 March 1994) is a British professional boxer. He held the British and Commonwealth cruiserweight titles from 2023 to 2024.
Chamberlain made his professional debut in January 2015, defeating Moses Matovu in a four-round points victory.
In September 2016, Chamberlain won the BBBofC Southern Area cruiserweight title with a points victory over Wadi Camacho.
He fought London rival Lawrence Okolie on 3 February 2018 at the O2 Arena in a Sky Sports card headlined "British Beef", losing a wide unanimous decision after having been knocked down twice. In preparation for the fight, Chamberlain visited Ukraine to spar with cruiserweights Oleksandr Usyk and Mateusz Masternak.
Chamberlain has worked as a sparring partner for former WBC heavyweight champion Deontay Wilder.
Sky Sports produced a documentary on Chamberlain's life, called 'Straight Outta Brixton'.