Joe suffered a serious knee injury in the summer of 2019 which ruled him out of the remainder of the season. Played for Burry Port and Coleg Sir Gar and featured in the same Wales U18s side as fellow Scarlets Osian Knott, Harri Doel, Jac Price, Jac Morgan and Sam Costelow. Spent a spell on loan with Ampthill RFC in 2021 before playing in the end-of-season Rainbow Cup for the Scarlets. Made a big impression during a breakthrough 2021-22 campaign, making seven appearances in the URC. After recovering from a knee injury, Roberts made a huge impact at the start of 2023, becoming a first-choice centre pick at the Scarlets and earning a first Wales call-up as part of the World Cup training squad.