Nixon's career began in 2007, when she starred as the motherless Sophy Hutton in the
BBC One costume drama series
Cranford. In 2008, she had supporting roles in the films
Wild Child and
Angus, Thongs and Perfect Snogging. In September 2008, she made her stage debut as Griet in a tour and London run of an adaptation of
Girl with a Pearl Earring. Nixon appeared in
Easy Virtue and played one of the leads in
Cherrybomb opposite
Rupert Grint and
Robert Sheehan, before starring in
Black Death. In 2011, Nixon played Josie in the Channel 4 TV comedy-drama series
Fresh Meat, and starred alongside
Michael Sheen,
Andrea Riseborough and
Iwan Rheon in
Resistance, an adaptation of an
Owen Sheers novel, which was released in the UK in November 2011. Nixon appeared in the musical film
Hunky Dory, which is set in 1976
Swansea, with
Minnie Driver,
Aneurin Barnard and
George MacKay, directed by
Marc Evans. The film premièred at the 55th
BFI London Film Festival on 25 October 2011, and was released officially on 2 March 2012 in the UK. Nixon starred alongside
Jaime Winstone and Aneurin Barnard in
Elfie Hopkins and the Gammons, a horror film about an aspiring teen detective who stumbles into her first real case when investigating the mysterious new family, the Gammons, in her neighbourhood. The film was released on 20 April 2012. In 2012, Nixon starred in the movie
Offender, a thriller about a man who sets up his own imprisonment in order to avenge the assault of his girlfriend. She also had leading roles in the ITV drama series "
Kidnap and Ransom" and the
BBC Two comedy-drama series
Hebburn, alongside
Chris Ramsey and
Vic Reeves. The sitcom is written by stand-up comic
Jason Cook and is based on his experiences of growing up in the
north-east of England. In June 2013, Nixon starred in "Greenshaw's Folly" in the sixth series of
ITV's ''
Agatha Christie's Marple'', with
Matt Willis,
Fiona Shaw,
Julia Sawalha,
Vic Reeves and
Martin Compston. She starred in the 2014
BBC One Wales television remake of
Dylan Thomas' radio drama
Under Milk Wood as Myfanwy Price. She also starred in the
Playhouse Presents one-off episode
The Dog Thrower, with
Matthew Perry and
Tim Key, which aired on 1 May 2014 on
Sky Arts. Nixon starred in the medical drama
Critical, with
Lennie James,
Emma Fryer and
Paul Bazely, that debuted on
Sky 1 on 24 February 2015. She also starred in a Welsh thriller titled
Kingdom of Rain, with
Julian Lewis Jones and
Robert Kazinsky. She took a lead role in the third season of
Outlander. In 2022, Nixon appeared as Donna in the BBC drama
Life and Death in the Warehouse. In 2023, Nixon played the role of Ms Parkinson in Channel 4's standalone drama
Consent. In 2026, Nixon stars in the one-woman show, Baby Brain, a semi-autobiographical play about a new mum struggling with postpartum psychosis. It premiered to a sold out performance in Porter's Cardiff, and received a 5-star review from The Edit Wales. The show will enjoy a UK tour in 2026, including the Edinburgh Fringe (Assembly). Nixon's autobiography, She Seems Fine To Me, about her personal experience with perinatal OCD, is published by Simon & Schuster. ==Personal life==