Gumbel is the son of Walter Gumbel, a German Jew from Stuttgart whose licence to practise law in that city was withdrawn in one of the early Nazi purges. Walter emigrated to Britain and became a successful barrister. Gumbel's mother, Muriel, served on the Greater London Council for many years between 1967 and 1986 and was Mayor of the Royal Borough of Kensington and Chelsea.An avowed atheist, Nicky Gumbel was converted to Christianity in his first year at Trinity College, Cambridge through reading the New Testament. He said, "I was enthralled. It was as if I had found what I had been looking for all my life".

Gumbel was educated at Eton and Trinity College, Cambridge.

After graduating in law in 1976, he followed in his father's footsteps and became a practicing barrister based at 3 Hare Court, Temple. Meanwhile, he became a regular worshipper at Holy Trinity Brompton, Knightsbridge. Then in 1982 he announced his decision to leave the bar to train for ordination in the Church of England. In 1983 Gumbel began theological studies at Wycliffe Hall, Oxford from where he graduated with an honours degree in theology. After some difficulty in finding a curacy, Gumbel joined the staff of his 'home' church of Holy Trinity Brompton Church in London as a curate in 1986. He was ordained priest in 1987.

Gumbel was officially installed as Vicar of Holy Trinity Brompton Church in September 2005 after the Reverend Prebendary Sandy Millar retired from stipendiary ministry and moved on to be an Assistant Bishop in the Diocese of London based at St Mark's Tollington Park in North London.

In 2007 he was awarded an honorary doctorate by the University of Gloucestershire (whose Chancellor is former Archbishop of Canterbury, George Carey) as recognition of his broad contribution to the wider church via Alpha.

In 1990 Gumbel took over the running of the Alpha Course that had been running there since 1973.The course was transformed under his leadership from being one designed for new Christians to one primarily for those outside the church who would not consider themselves as Christians.

He is the author of a number of books related to the Alpha course, including Questions of Life, which has sold over 1,000,000 copies. Voted "Christian Book of the Year" in 1994, it has been published in 48 languages. Other related books include Why Jesus, Searching Issues, Telling Others, A Life Worth Living, Challenging Lifestyle, Heart of Revival and 30 Days.

Nicky Gumbel is married to Pippa and they have three children.