Born in England, he represents Wales at international level after qualifying on ancestry grounds.

His 100th Saracens match came in 2019, when he scored a hat-trick in 28 minutes against Gloucester in the Premiership Rugby semi-final.

[3] He was also a replacement as Saracens won the 2019 European Rugby Champions Cup Final.

[5] Tompkins started the final as Saracens defeated Sale Sharks to win the Premiership title in 2023.

[8] On 1 February 2020, Tompkins made his international debut for Wales as a first-half injury replacement and scored a try in the 42–0 win over Italy.