Brown Findlay was cast in the lead role of seventeen year-old Emilia Conan Doyle for Albatross, a 2011 British coming-of-age comedy drama film directed by Niall MacCormick, co-starring Julia Ormond, Felicity Jones and Sebastian Koch. The film's premise revolves around a teenage aspiring Writer entering the lives of a dysfunctional family living in the south coast of England, with bookish young women meeting up with a peer who lacks any boundaries or inhibitions. Next, she was cast in two episodes of the British science fiction comedy-drama television show Misfits. Brown Findlay appeared in the first-season finale as a wholesome religious girl whose superpower is convincing everyone to abandon their delinquent behaviour in favour of celibacy.

In 2012, Brown Findlay became the face of Dominic Jones' jewellery line, and she was cast in Not Another Happy Ending by John McKay, and in the miniseries Labyrinth, based on the novel of the same name written by Kate Mosse, portraying Alaïs Pelletier. In 2012, Brown Findlay was cast as Beverly Penn in the film adaptation of the novel Winter's Tale (2014) with Colin Farrell and Russell Crowe.

In 2014, she appeared as Beverly Penn in the film adaptation of the Mark Helprin novel Winter's Tale. In 2015, she co-starred in Paul McGuigan's Victor Frankenstein as Lorelei, the Esmerelda-like acrobat. In 2016, she joined the cast of the new biopic feature film, England is Mine, about the early life and career of English singer Morrissey, who co-founded the indie rock band The Smiths.

In May 2015, Brown Findlay made her theatre debut at the Almeida Theatre, London, as Electra in a new adaptation of The Oresteia to positive reviews. The production later transferred to the Trafalgar Theatre in London's West End. The Writer and Director was Robert Icke, who cast Brown Findlay in his production of Uncle Vanya at the same venue in February of the following year.

In 2016, she joined the cast of the biopic feature film, Steven, about the early life and career of English singer Morrissey, who co-founded the indie rock band The Smiths. The film premiered at the Edinburgh Film Festival in 2017, with "Dunkirk" actor Jack Lowden in the lead role.

2017 also saw the debut of This Beautiful Fantastic, an indie film in which Brown-Findlay starred as Bella Brown, a repressed foundling who forms a new life through her relationships with a curmudgeonly neighbor (Tom Wilkinson), a gifted cook (Andrew Scott) and an eccentric Inventor (Jeremy Irvine).