An Irish native, Justine continues to enjoy a successful career across stage and screen. Most recently, Justine appeared as ‘Jo Mulligan’ in Alma Mater at the Almeida – about which one critic wrote: ‘Is there a more quietly essential actress these days than Justine Mitchell …?’ – and ‘Grace’ in Rachel O’Riordan’s adaptation of Brian Friel’s enduring Faith Healer, which opened at the Lyric Hammersmith to critical acclaim. Justine was singled out for giving a ‘profoundly powerful performance’, imbuing Grace with a ‘magnificent fury’. Other theatre credits include Dancing At Lughnasa (National Theatre), Shipwreck (Almeida), The Way of the World (Donmar Warehouse) and Beginning (National/West End) – to name but a few – all showcased her versatility and range. TV credits include the role of ‘Paula’ in Sally Rooney’s follow up to Normal People, Conversations With Friends (BBC), ‘Eleanor Philby’ in A Spy Among Friends (ITV) and ‘Elaine Lynch’ across three seasons of the Smother (RTE/Peacock) – for which she received an IFTA nomination for Best Supporting Actor. Feature credits include The Mauritanian, alongside Tahar Rahim, Jodie Foster and Benedict Cumberbatch (Dir: Kevin Macdonald), which was nominated for Best Film at the BAFTAS and Critics Choice in 2021.

Justine received The Irish Times/ESB Theatre Award 2002 for Best Supporting Actress in Bash and Blithe Spirit at The Gate Theatre, Dublin. She also received the UK Theatre Award 2015 for Best Supporting Actress in For Services Rendered performed in Chichester.

Most recently, Justine reprise her role in the latest instalment of Sharon Horgan’s Bad Sisters.