Myhill begin his career with the Scarlets academy, and represented the team for six seasons before joining Cardiff Rugby.

[1] Myhill attended Glan-y-Mor Comprehensive School and Coleg Sir Gâr, where he played for their rugby team, as well as with the Burry Port RFC youth side.

[2] Myhill was part of the Scarlets academy, and made a positional change from back row to hooker while playing at U18 level.

So far in his career, Myhill has had to settle for a back-up role in the Scarlets squad, being behind the likes of Matthew Rees, Ken Owens and Emyr Phillips in the pecking order.

[1][2] Following injuries to other hookers in the squad, Myhill was surprisingly called up by Wales for their test against New Zealand in October 2021.