In 2014, Theobold made a guest appearance on the TV sitcom Lovesick (formerly known as Scrotal Recall). In 2015, she appeared in two episodes of Last Tango in Halifax as Holly, and an episode of Call the Midwife. She starred as Sarah, a housekeeper at a stately home and one of the main characters, in the third series of The Syndicate which aired in spring 2015. She is also the voice Actress for Tracer in the video games Overwatch and Heroes of the Storm and starred in the E4/Netflix original series Crazyhead alongside Susan Wokoma. In 2016, it was announced that Theobold would star in Absentia along with Stana Katic and Patrick Heusinger.