Born in Rochdale, Lancashire, UK, Clegg was educated at the Manchester Grammar School and went on to read Natural Science (specializing in experimental physics) at Cambridge University. After graduating, he spent a year at Lancaster University where he gained a second MA in Operational Research, a discipline originally developed during the Second World War to apply the power of mathematics to warfare. It has since been widely applied to problem solving and decision making in business.

From Lancaster, he joined British Airways, where he formed a new department tasked with providing all PC hardware, software and consultancy to the airline. When this was successfully running, he set up the Emerging Technologies Group, a team of the most eccentric but talented staff in the company, who researched and trialled technologies from fingerprint recognition to electronic cash. This emphasis on innovation led to training with Dr. Edward de Bono, and in 1994 he left BA to set up his own creativity consultancy, running courses on the development of new ideas and products, and the creative solution of business problems. His clients include the BBC, the Met Office, British Airways, GlaxoSmithKline, Sony, Royal Bank of Scotland and many other blue-chips.

Clegg is a regular speaker and has spoken at a range of venues, from Oxford and Cambridge Universities to the Dana Centre at the Science Museum . His book A Brief History of Infinity was launched with a sell-out lecture at the Royal Institution in London. He is also a regular contributor to both radio and TV programmes and writes regular columns, features and reviews for numerous magazines, including PC Week, Computer Weekly, Personal Computer World, Innovative Leader, Professional Manager, BBC History Magazine, Good Housekeeping, Nature and House Beautiful.

Clegg is a Fellow of the Royal Society of Arts.

His books have been translated into many languages, including German, Spanish, Portuguese, Chinese, Japanese, Polish, Turkish, Norwegian, Thai and Indonesian.

His latest UK book Ecologic was published by Eden Project Books on 30 January 2009. In the US, his most recent title is Before the Big Bang, published by St. Martin's Press in August 2009.

Clegg lives in Wiltshire with his wife and twin children.