Tony McNamara attended the Victorian country boarding school Assumption College as a day boy. Early in his career, he worked in the money market in Sydney and London. He also worked as a debt collector, grill cook and waiter. During a short stay in Rome he decided to become a writer.

Back in Australia, he enrolled in a writing course at Royal Melbourne Institute of Technology, which he failed. He then moved to Sydney where he graduated with a BA in Film and TV from the Australian Film Television and Radio School in 1996.

As well as writing plays and screenplays and directing films, he has written extensively for television, including forming part of the writing team for the television series The Secret Life of Us.

He was the script-writer for the highly successful and widely praised films The Favourite and Poor Things.