She has appeared in Mister Eleven and Beautiful People (2009), Thorne: Sleepyhead (2010), Spotless (2015), Catastrophe (2015–2019), Trust Me (2019), I May Destroy You and Trying (2020), Viewpoint (2021), Riches and The Sandman in 2022.
Niles was born in Thornton Heath, south London, and was the youngest daughter of three to her father an electrician, and her mother a care nurse, both Barbadians who arrived in Britain in the late 1950s.
In 2013 and 2014, she worked with the Royal Shakespeare Company as Charmian in Antony and Cleopatra, performing at Stratford Upon Avon and touring to Miami and The Public Theater New York.
In 2017, she appeared as Carmen in Guillermo Calderón's play B at the Royal Court alongside Paul Kaye, Aimee-Ffion Edwards and Danusia Samal.
[5][6] She recently appeared in Sarah Gavron's award-winning film Rocks, Michaela Coel's I May Destroy You and Netflix's The Sandman.