His parents were both members of the Communist Party. Stephen Twigg joined the Labour Party at the age of 15. He was the first pupil from Southgate Comprehensive school to obtain a place at Oxford University. He studied politics, philosophy and economics at Balliol College. He was the first out-gay president of the National Union of Students (NUS) in 1990. Twigg was briefly secretary of the Fabian Society.

He became a Councellor in Islington, London in 1992 and became chief whip. He ran for the leadership of the Council in 1996 and lost by one vote. He became an MP for the first time winning the Enfield Southgate seat at the general election in 1997. His defeat of the sitting MP, Michael Portillo, was a great upset for the Conservative Party, particularly its right wing. Stephen Twigg's win was unexpected and was the result of a 17.4% swing in the constituency to the Labour Party. Stephen Twigg and Ben Bradshaw were the first British MPs to be elected as out-gays.

In the general election of 2001 the Conservative Party were hoping to regain the seat but Stephen Twigg held the seat. He was given the job of deputy to Robin Cook, the Leader of the House of Commons, with the rank of Parliamentary Secretary. He was promoted on 29th. May 2002 when he was moved to the Department for Education and Skills to become a Parliamentary Under-Secretary.