Kirby Myhill has been a member of the Scarlets since 2011, after having been part of the Scarlets Academy. Born in Pembrey, Myhill was educated at Glan-y-Mor School and Coleg Sir Gar and grew up playing rugby for Burry Port and Kidwely.
Myhill made his senior debut for the Scarlets in a league match at Leinster in March 2011 as a replacement. It was his only appearance that season, but the following season he made 13 appearances, including 4 starts. He scored his only try to date against the Cardiff Blues in the LV Cup win on 23 October 2011.
Myhill was named captain of the Wales Under-20 team for the 2012 Six Nations and the IRB Junior World Championship, in which Wales finished 3rd.