His grandmother was Katherine McQuiggan from Philadelphia but he grew up with fifties singer Georgia Gibbs, who married his grandfather Frank in the early 1960s and whose million-selling singles include "Kiss of Fire", "Dance with Me, Henry" and "Tweedle Dee". She has a star on the Hollywood Walk of Fame.

Gervasi's first position was to work for the Poet Laureate of the United Kingdom, Ted Hughes at the Arvon Writing Foundation, founded by two young poets, John Fairfax and John Moat, in 1968. After completing his degree, he subsequently worked for John Calder of the Samuel Beckett archive helping to arrange a vast sale of Beckett's personal papers at Sotheby's in 1989, including Beckett's own annotated version of Waiting for Godot which sold to Trinity College, Dublin.

Gervasi was educated at Westminster School, and then read modern history at King's College London. As a teenager in 1981, Gervasi befriended Canadian metal band Anvil when they toured London and became a roadie for the band on three tours, eventually becoming close friends until a falling out in 1986.

Gervasi directed Anvil! The Story of Anvil, a documentary of the Canadian heavy metal band, Anvil, who had then been together for over 30 years. Gervasi first met Anvil on 21 September 1982, after a gig at The Marquee Club in London. He introduced himself to the band as "England's number one Anvil fan". He subsequently became a roadie for the band on their 1982, 1984 and 1985 tours, and was given the nickname "teabag" by the band. He reunited with Anvil after a break of 20 years, and started shooting a rockumentary about them in November 2005.

He is attached to write and direct My Dinner with Hervé, a biopic of actor Hervé Villechaize, based on Gervasi's own interviews with the diminutive Frenchman, conducted only days before the actor committed suicide in 1993. The film will star Emmy Award- and Golden Globe-winning actor Peter Dinklage and is to be produced by Oscar-winning Schindler's List scribe Steven Zaillian. The movie will be on HBO.

Gervasi moved to Los Angeles in 1995 to attend the graduate screen-writing programme at UCLA Film School, where he twice won the BAFTA/LA scholarship. While in the programme, he supported himself by working as a Journalist, writing for newspapers and magazines, including The Sunday Times, The Observer, and Punch.

From 1999 to 2000, he was the voice of Jaguar Cars on US radio and television.

Gervasi got his film-writing start with The Big Tease, which he co-wrote with Craig Ferguson. He went on to pen The Terminal, made into a film in 2004 directed by Steven Spielberg and starring Tom Hanks. According to London's The Daily Telegraph: "He is one of only two English screenwriters to have their scripts made into movies by Steven Spielberg. The other is Tom Stoppard [for Empire of the Sun]."

On 14 May 2006, Geri Halliwell gave birth to their daughter, Bluebell Madonna Halliwell.

The film premièred at the Sundance Film Festival in January 2008, and won Audience Awards at the 2008 Sydney Film Festival, Los Angeles Film Festival and Galway International Film Festival.

In 2009, the Motion Picture Association of America opened the category of Best Picture nominees from 5 to 10. In October 2009, Anvil! The Story of Anvil was the first screener to be sent out for considering of the expanded Best Picture category as well as for Best Documentary. There was disappointment when Anvil was one of the higher-profile films not short-listed in the Best Documentary category.

In 2010, he married British theatre Producer Jessica de Rothschild (b. 1974) of the Rothschild family and daughter of British financier Evelyn Robert de Rothschild.

In 2012, Gervasi directed Hitchcock starring Anthony Hopkins as Alfred Hitchcock, Helen Mirren as his wife Alma, and Scarlett Johansson as Janet Leigh. Other cast members included Jessica Biel, Danny Huston, Michael Stuhlbarg, James D'Arcy and Michael Wincott.