Sion joined Cardiff City's Academy setup at the age of seven. During 2016/17, he made his U23 debut at the age of just 16.
A clever midfield player, Sion is known for his determination and ability to score a variety of goals. His apprenticeship began on July 1st, 2017.
Sion has made 15 competitive appearances during the 2018/19 season for Cardiff City's U18 side, scoring 11 times, as of April 16th, 2019. He recently returned to the side after a three month lay off through injury.