Poppy Gustafsson was born in Huntingdon on 24 August 1982. She studied mathematics at the University of Sheffield, graduating in 2003, and qualified as a chartered accountant in 2006 after training at Deloitte.
She worked at Amadeus Capital Partners and joined Autonomy in 2009 as a corporate controller. Darktrace was created inside Mike Lynch's Invoke Capital in 2013 with former Autonomy managers, and she co-founded it as chief financial officer.
She became co-CEO in 2016 and sole CEO in 2020. Darktrace listed in London in April 2021 at about £2.5 billion. In January 2023 a short-seller report alleged accounting errors, and in July 2023 EY found a small number of errors that were not material.
She stepped down as CEO in September 2024, and Thoma Bravo completed its $5.3 billion takeover on 1 October 2024. She became a minister in October 2024 and a life peer in November 2024, then resigned as minister on 5 September 2025.