"I hurt my back and at that point was deciding what to do university-wise and I thought I would try for drama college because I knew you could do some dancing there but it didn’t have to take over everything. It was only really when I went to drama college that that world [acting] opened up to me and I fell in love with it and became obsessed like everybody else.”
In 2003, Amuka-Bird married actor Geoffrey Streatfeild, whom she met while touring with the RSC in Japan. The marriage lasted seven years.
Amuka-Bird's theatrical credits include Welcome to Thebes (National Theatre); Twelfth Night (Bristol Old Vic, for which she won an Ian Charleson Award nomination in 2004 for playing Viola); World Music (Crucible Theatre, Sheffield, and Donmar Warehouse); Top Girls (Oxford Stage Company); A Midsummer Night's Dream, The Tempest and The Servant of Two Masters (RSC); Doubt: A Parable (Tricycle Theatre).
Her film credits include The Omen (2006 remake), Cargo, Almost Heaven as well as the screen adaptation of Alexander McCall Smith's novel The No. 1 Ladies' Detective Agency. On television, Amuka-Bird has appeared in Spooks, The Line of Beauty, The Last Enemy, Robin Hood, Torchwood, and a recurring role in the reimagined BBC apocalyptic series Survivors. In 2010 she appeared as Det. Supt Gaynor Jenkins in the BBC's Silent Witness.
She appeared in Small Island, the BBC adaptation of Andrea Levy's award-winning novel, broadcast in December 2009. In June 2016 it was announced that she and Phoebe Fox would star in the production of Zadie Smith's novel NW. It was broadcast on BBC2 on 14 November 2016 and Amuka-Bird received a BAFTA for Best Actress.
On Christmas Day 2017 she was heard as the voice of the Glass Woman in the Doctor Who Christmas Special "Twice Upon a Time" broadcast on BBC1 and around the world.