Roisha was born in Belfast and grew up in South London before studying modern and medieval languages at the University of Cambridge.
Roisha began her civil service career in the Department for Culture, Media and Sport, working on the Government's bid to host the 2012 Olympic Games. She then ran the Mayor of London's office for eight years from 2008, as the city navigated economic downturn, upgraded and developed new transport systems, and hosted the Olympic Games in 2012.
Roisha was Director of Strategy and Governance in the Metropolitan Police Service from 2016 to 2022. She then ran her own consultancy before being appointed Chief Executive of the John Whitgift Foundation in 2024. The Foundation was established in 1596 by the then Archbishop of Canterbury to care for and educate the people of Croydon.
Roisha lives in South London with her three children.