Maesteg RFC was formed in 1877 in the Llynfi Valley, in the county of Glamorgan. They were county league champions 1912 to 1913. The 1949 team completed their season without losing a single game. In 1978 and 1979 they were the Whitbread league champions. In 1982 they played the Irish Wolfhounds, Crawshays RFC, Toronto Welsh RFC, German Federation and the New Zealand Māoris; they held the latter to a 10-10 draw. These games were thought at the time to be part of the centenary season of the club. It was later discovered that this was untrue, as the centenary was five years earlier.
Maesteg were promoted to the Welsh Premier Division in 2005, but were relegated back to division one when they came bottom of the league in the 2007/08 season.