Theroux was born in Singapore, the younger son of the American travel writer and novelist Paul Theroux and his British first wife, Anne Castle. His elder brother is the writer and television presenter Marcel Theroux. He is the cousin of American actor Justin Theroux. He moved to the UK when he was 4, and was brought up in London.Theroux was educated for a couple of years at Allfarthing school then moved to Westminster School (where he was a friend and contemporary of the comedians Adam Buxton and Joe Cornish). Another of his contemporaries was Liberal Democrat politician, and Deputy Prime Minister of Great Britain, Nick Clegg with whom he travelled to America. He then went to Magdalen College, Oxford where he gained a first class degree in modern history and was noted for his film reviews for the Grapevine magazine.

His first journalism job was at Metro Silicon Valley, an alternative free weekly newspaper in San Jose, California. In 1992 he was hired as a writer for Spy magazine. He was also working as a correspondent on Michael Moore's TV Nation series, for which he provided segments on off-beat cultural subjects, including Avon ladies in the Amazon, the Jerusalem syndrome, and the attempts by the Ku Klux Klan to rebrand itself as a civil rights group for white people. When TV Nation ended he was signed to a development deal by the BBC, out of which came Louis Theroux's Weird Weekends. He has guest-written for a number of publications including Hip-Hop Connection and he continues to write for The Idler.

Louis Theroux's Weird Weekends

In Weird Weekends (1998–2000), Theroux followed marginal, mostly American subcultures like survivalists, Black nationalists, White supremacists and porn stars, often by living among or close to the people involved. Often, his documentary method subtly exposed the contradictions or farcical elements of some seriously-held beliefs. Theroux himself describes the aim of the series as

When Louis Met...

In When Louis Met (2000–2002), Theroux accompanied a different British celebrity in each programme as they went about their day-to-day business, interviewing them about their lives and experiences as he did so. His episode about the DJ and charity fundraiser Sir Jimmy Savile When Louis Met Jimmy was voted one of the top fifty documentaries of all time in a survey by Britain's Channel 4. In When Louis Met the Hamiltons, the disgraced Tory MP Neil Hamilton and his wife Christine were arrested following false allegations of indecent assault during the course of filming. In When Louis Met Max Clifford, Max Clifford tried to set Louis up. However, it backfired when Max Clifford was caught lying, as the crew was still recording his live microphone during a conversation. After this celebrity series concluded, a retrospective was aired, called Life with Louis. He was meant to do a similar program with Michael Jackson before Martin Bashir completed his documentary for Channel 4, but it was cancelled.

BBC Two Specials

In these special programmes (2003), Theroux returned to American themes, working at feature-length, this time with a more natural tone. In March 2006, he signed a new deal with the BBC to make ten films over the course of three years.

On April 1 2010, during an interview to the Israeli newspaper Yedioth Ahronoth, Theroux announced that one of the upcoming documentaries will be shot in Israel, and will follow the Israeli Settlers. Answering the question "Have you considered making an episode of your show in Israel?", Theroux replied: "More than considered. In 2010 I will make an episode about teenage settlers."

His first book, Travels in American Subcultures, was published in Britain in 2005. In this book, Theroux returns to America to find out what has happened in the lives of some of the people he featured in his television programmes since he last saw them.

He lives in the London district of Harlesden with his girlfriend, Nancy. They have two children, Albert and Frederick.

1996 Emmy Awards:

• Nominated: Outstanding Informational Series for TV Nation

British Academy Television Awards 2001:

• Won: Richard Dimbleby Award for the Best Presenter (Factual, Features and News) for Weird Weekends

2002 Royal Television Society:

• Nominated: Best Presenter for When Louis Met

British Academy Television Awards 2002:

• Won: Richard Dimbleby Award for the Best Presenter (Factual, Features and News) for When Louis Met
• Nominated: Flaherty Documentary Award for When Louis Met the Hamiltons

Journalists John Safran and Harmon Leon cite him as an "important influence".