In 2020, Mulligan starred in Emerald Fennell's black comedy thriller film "Promising Young Woman", alongside Bo Burnham and Alison Brie. She also served as an executive producer on the film, which debuted at the 2020 Sundance Film Festival to great acclaim. The website Rotten Tomatoes lists the film's approval rating as 92%, with a critics consensus reading, "A boldly provocative, timely thriller, "Promising Young Woman" is an auspicious feature debut for writer-director Emerald Fennell -- and a career highlight for Carey Mulligan." Due to the COVID-19 pandemic the film's release was delayed to 25 December 2020.