She was born in Santiago, Chile where her Hungarian Jewish parents had fled during World War II.
Mahr was inspired to study journalism by Jean-Luc Godard's film À Bout de Souffle.
The British Council staged Mahr retrospectives in her countries of origin Hungary and Chile.
She received the Fox Talbot Award from the National Museum of Photography, Film and Television in 1989.
A book titled Between Ourselves: The Photographs of Mari Mahr was published in 1998, featuring contributions by Amanda Hopkinson.