Kemsley began stand-up in 2011 and within months won the Funny's Funny contest. In 2012, she won Bath Comedy Festival New Act of the Year and Brighton Comedy Festival New Act of the Year and was named by
Rhod Gilbert as one of the Ten Must See Comics of 2012. Kemsley has appeared on ''
Sam Delaney's News Thing, Roast Battle, 8 Out of 10 Cats Does Countdown and 8 Out of 10 Cats. She and then-fiancé Bobby Mair appeared on a Viceland reality show in 2017, entitled Bobby & Harriet Get Married'', featuring their wedding, officiated by comedian
Romesh Ranganathan. As an actress, she has appeared in the film
Bonobo and on TV on
Damned and
Doctor Foster. She also provided the voice of Nashandra, the final boss of the video game
Dark Souls II. In March 2025, she starred in the first series of
LOL: Last One Laughing UK, hosted by
Jimmy Carr and
Roisin Conaty. ==Personal life==