In 1986, she joined the Royal Shakespeare Company, and the Royal National Theatre, the first female musical Director with both companies. In 1990, she co-founded the theatre company Phoebus Cart with her husband Mark Rylance.
Since the opening of the Shakespeare's Globe Theatre in 1997, van Kampen has been the Director of Theatre Music, creating both period and contemporary music for 30 of the Globe's productions – including the 'jazz' Macbeth in 2001, and The Golden Ass in 2002, which contained a 30-minute opera Cupid and Psyche.
In spring 2007, she received the Vero Nihil Verius award for Distinguished Achievement in the Arts, conferred upon her by Concordia University in Oregon, United States. Together with Mark Rylance and Jenny Tiramani, she received the 2007 Sam Wanamaker Award for the founding work during the opening ten years at Shakespeare's Globe Theatre.
Her daughter Nataasha died of a suspected brain haemorrhage on a FLIGHT from New York in July 2012 at the age of 28.
Farinelli and the King is van Kampen's historical play about the relationship between Farinelli, the castrato, and the Spanish King Philippe V, first performed at Sam Wanamaker Playhouse in February and March 2015, and at the Duke of York's Theatre in the West End, London from September to December 2015, with Mark Rylance as Philippe V. it received six Olivier Award nominations including Best Play. In 2016 she directed Mark Rylance in Nice Fish at the St. Ann's Warehouse, New York. The production subsequently transferred to the Harold Pinter Theatre