[3][4] She has appeared on British TV and radio panel shows, including 8 Out of 10 Cats,, Never Mind the Buzzcocks, A League of Their Own, Mock the Week, Would I Lie to You?, QI, Just a Minute, Safeword, and Have I Got News for You.

As an actress, Ryan has appeared on several television sitcoms in the UK, including Campus, Episodes, and her Netflix show The Duchess.

[13] In her spare time she performed at open mic nights for her own entertainment, and by graduation she had developed a basic comedy routine.

[14] After graduation, Ryan continued working for Hooters as a corporate trainer, travelling around Canada to train other waitresses, and helping to open the then-only UK branch in Nottingham.

Her partner at the time, Wade McElwain, wanted to explore London,[15] so she agreed to do so for an initial month from summer 2007, moving there permanently from January 2008.

[22] In February 2017, Netflix released Katherine Ryan: In Trouble, featuring her stand-up comedy live performance at the Hammersmith Apollo in London, during that tour.

[25] As an actress, Ryan has appeared on numerous television series in the UK, including the sitcoms Campus,[26][27] Episodes[28] and Badults.

[29] Ryan starred in the Netflix comedy The Duchess, based on a single mother's life in London; she is credited as its writer, executive producer, and creator.

[30] On 6 June 2014, YouTube comedy duo Jack and Dean released a music video for their song "Consent" featuring Ryan in an acting role.

For her comedy work, Ryan won the 2008 Funny Women Award and was described as "the funniest new female stand up in Britain" by a national newspaper.

In 2013, Ryan was the subject of controversy over her participation on Mock The Week in a segment "Unlikely Lines From a Cosmetics Commercial", where one of her jokes was "We don’t test any of our products on animals.

[39][40] In another interview, she was accused of racism by some viewers on social media when she attempted to encourage a female Sri Lankan designer by saying "You need to really back yourself.