Dignified, with an exquisite voice, Marianne Jean-Baptiste was hardly known in her native Britain and completely unknown in the USA until the release of Mike Leigh's acclaimed "Secrets & Lies" (1996). Cast as Hortense, an Afro-British young woman who seeks out her birth mother and discovers the latter is a lower-class white woman. Hortense is then slowly integrated into her birth mother's family, a group filled with unstated emotions and buried truths all of which are manifested in anger and hostility. Jean-Baptiste had previously worked with director Leigh on the 1993 stage production of "It's a Great Big Shame". The experienced actress has also appeared with the Cheek By Jowl company, playing both Mariana and Mistress Overdone in "Measure for Measure", was at the Theatre Royal Stratford, in "Running Dream", was featured in productions at London's Royal National Theatre and also with companies in Yorkshire and Manchester. Jean-Baptiste received some notice for "Ave Africa", which she both wrote and performed in. An accomplished singer, she has recorded a blues album as well.

Prior to her breakthrough role, Jean-Baptiste had a small role as a nanny in Hanif Kureishi's "London Kills Me" (1993), which focused on the lives of homeless teens living in the London Underground. Despite the international attention earned with "Secrets & Lies", including a Golden Globe nomination and pre-Oscar buzz, it was reported in January 1997 that Jean-Baptiste was unemployed and "living on the dole" in London. That changed, however, when she joined the cast of Noah Baumbach's second feature "Mr. Jealousy" (1998).