Cerys started performing stand-up comedy at the age of 15, when Natalie Haynes ran a workshop at their school. They were social secretary of the KCL Comedy Society and wrote and performed sketches and stand-up throughout their undergrad degree.

In 2016, they joined Steve Cross' Talent Factory and began performing science themed stand-up comedy. They have performed at the Science Showoff (as well as Geek Showoff, History Showoff, and Books Showoff), Nerd Nite, the Variable's Presents, Dr Jigg's Bowson's Charming Science Friends, and a number of other science and/or geekery themed comedy nights.

They performed with the Agony Auncles of Science, a science themed improv night that promises to solve all your problems, at the Edinburgh Fringe 2017. The show received a 5 star review and made it into Wired's Top 10 Science Shows at the Fringe. 

Cerys is taking their new show The Unfortunate Bisexual with Rach Wheeley to the Edinburgh Fringe. They have written two solo shows, the Invention of Lesbianism and A Unifying Theory of Gay.