Olivia Mathias (born 12 October 1998) is a Welsh professional triathlete. She competed at the 2022 Commonwealth Games, in Mixed relay, winning a silver medal.
She competed at the 2018 Commonwealth Games. In August 2019, she won silver in the women's U23 race at the Triathlon World Championships in Lausanne, Switzerland.
She competed at the 2022 Europe Triathlon Cup Kitzbühel, winning a gold medal.