Ria Zmitrowicz is a British actress. She is known for her work in theatre, earning WhatOnStage and Manchester Theatre Award nominations, and her role in the BBC drama Three Girls (2017).

Zmitrowicz was born in Spain and grew up in Berkshire, Surrey, and Hampshire. She attended the Sixth Form College, Farnborough.

She joined the National Youth Theatre (NYT) at sixteen and moved to London when she was eighteen.

In 2013, she played Wilma Grey in the two-part ITV crime drama Murder on the Home Front. She also had a recurring role as Jodie in the E4 comedy-drama series Youngers. The following year, she joined the cast of the sitcom The Midnight Beast as Hope for its second series, also on E4, and the ITV period drama Mr Selfridge as Sarah Ellis, a recurring role she would play for the latter three series.

Zmitrowicz made her feature film debut with a small role in the 2015 film Kill Your Friends.

She starred as Amber Bowen, one of the titular victims, in the BAFTA-winning three-part BBC One miniseries Three Girls, based on a true story with the names changed. In 2018 Zmitrowicz was named a Breakthrough Brit in the BAFTA awards.

She plays Roxy Monke in the 2023 Amazon Prime adaptation of Naomi Alderman's science fiction novel The Power.