Hamm began his career on the London fringe before becoming resident director of the Royal Shakespeare Company where he mainly focused on working with contemporary playwrights, including Howard Barker, Edward Bond and Arthur Miller.

In 1996, he directed Talk of Angels (Miramax) starring Polly Walker and Vincent Perez, an epic love story set in the early days of the Spanish Civil War.

He then directed the romantic comedy Martha, Meet Frank, Daniel and Laurence, a Film Four and Miramax co-production written by Peter Morgan and starring Joseph Fiennes.

Screenplay by acclaimed Irish novelist, Colin Bateman, the drama is a fictionalized account of political enemies Ian Paisley and Martin McGuiness's real journey to peace and friendship in the 2006 St Andrews Agreement.

In 2021, Hamm directed and produced his latest feature film, Gigi & Nate, starring Marcia Gay Harden, Diane Ladd, Charlie Rowe and Josephine Langford.

Hamm's work in British television includes Play on One: Out of the Blue, starring Catherine Zeta-Jones and Colin Firth for the BBC, and the highly acclaimed series Rik Mayall Presents for Granada.

Season one, Full Circle: Los Angeles, starring Minka Kelly, Tom Felton, David Boreanaz, Kate Walsh, Ally Sheedy and Julian McMahon, premiered in 2013.

Season two, Full Circle: Chicago, starring Terry O'Quinn, Calista Flockhart, Kate Burton, Chris Bauer, Rita Wilson and Brittany Snow premiered in 2015.