Old Illtydians were formed in September 1928 as Saint Illtyds Old Boys Rugby Club.

Due to the club's connections to St. Illtyds school the team managed to keep playing for all but two years during the Second World War.

In 1966 the club were successful in gaining membership to the Welsh Rugby Union and in 1967 they moved to their new ground in Leckwith.

In 2014 thanks to the work of Chairman John Manders the club secured a new long term lease on a ground in Moorland Park, Splott.

This puts the club in closer proximity to its clubhouse, which is based on Splott Road.