Ridley was educated at Eton and Magdalen College, Oxford, where he received a doctorate in zoology before commencing a career in journalism. Ridley worked as the science editor of The Economist from 1984 to 1987 and was then its Washington correspondent from 1987 to 1989 and American editor from 1990 to 1992.

Ridley was non-executive chairman of the UK bank Northern Rock from 2004 to 2007, in the period leading up to the bank's near-collapse.

He was the first chairman of the International Centre for Life, a science park devoted to life sciences in Newcastle, and he served in this position for seven years. He formerly had been a governor of the Ditchley Foundation, which organises conferences at its stately home in Oxfordshire. He is a distinguished supporter of the British Humanist Association.

He is the author of several works of popular science:

• 1993 Sex and the Evolution of Human Nature

In Lewis Carroll’s Through the Looking-Glass, Alice meets the Red Queen who runs everywhere but stays in the same place. This book champions a Red Queen theory for the evolution of sexual reproduction: that it was invented to keep changing the genetic locks so as to remain one step ahead of constantly mutating parasites. The Red Queen also addresses dozens of other riddles of human nature and culture — including why men propose marriage, the method behind our maddening notions of beauty, and why the human brain may be like the peacock’s tail — a seduction device.

• 1996 Human Instincts and the Evolution of Cooperation

In The Origins of Virtue, Ridley argues that the human mind has evolved a special instinct for social exchange that enables us to reap the benefits of co-operation, ostracise those who break the social contract and avoid the trap of being 'rational fools'. It traces the evolution of society first among genes, then among cells, then in ants, vampire bats, apes and dolphins, and finally among human beings. Along the way, it plays games with computers, traces the psychological roots of football riots, finds trade to be ten times as old as economists believe, compares dead mammoths to lighthouses, explains the evolution of human emotions and shows how to save the rain forest. In an interview with Foreign Policy magazine, former US President Bill Clinton named this book as one which had influenced his thinking.

• 1999 The Autobiography of a Species in 23 Chapters

The human genome, the complete set of genes in 23 pairs of chromosomes, is an 'autobiography' of our species. Spelled out in a billion three-letter words using the four-letter alphabet of DNA, the genome has been edited, abridged, altered and added to as it has been handed down, generation to generation, over more than three billion years. This generation is the first to read this book, and to gain hitherto unimaginable insights into what it means to be alive, to be human, to be conscious or to be ill. By picking one newly discovered gene from each of the 23 human chromosomes, and telling its story, Matt Ridley recounts the history of our species and its ancestors from the dawn of life to the brink of future medicine. James Watson, co-discoverer of the structure of DNA, described the book as "lucid and exhilarating".

• 2003 Genes, Experience, & What Makes Us Human, also later released under the title The Agile Gene: How Nature Turns on Nurture in 2004

This book chronicles a new revolution in our understanding of genes, recounting the hundred years' war between the partisans of nature and nurture to explain how this paradoxical creature, the human being, can be simultaneously free-willed and motivated by instinct and culture. The emerging truth is far more interesting than a stale antithesis between heredity and environment. Nurture depends on genes, and genes need nurture. Genes not only predetermine the broad structure of the brain; through the pattern of their turning on and off they also absorb formative experiences, react to social cues and even run memory. They are consequences as well as causes of the will.

• 2006 Francis Crick: Discoverer of the Genetic Code

A biography of Francis Crick that won the Davis Prize for the history of science from the US History of Science Society.

Ridley also edited The Best American Science Writing 2002, one of a series of annual science writing anthologies edited by Jesse Cohen, and contributed a chapter to How a Scientist Changed the Way We Think, a collection of essays in honour of his friend Richard Dawkins (edited by his near-namesake Mark Ridley).

• 2010 The Rational Optimist: How Prosperity Evolves, HarperCollins. Reviewed in Nature 465, 294—295 (20 May 2010)

Ridley creates a wide-ranging history of human society from early hunter-gatherer groups into the early 21st century. He argues that human beings have an often underestimated capacity for change and social progress. From early on in human evolution, Ridley writes, trade and other kinds of exchanges between groups "gave the Species an external, collective intelligence". He continues with histories of socio-economic progress under free market capitalism and democratic civil institutions. He then dismisses what he sees as overly pessimistic views of global climate change and Western birthrate decline. The book contains numerous graphs depicting social changes, such as how world GDP per person grew from about $1,000 in 1900 to $6,000 in 2000.

He is the son and heir of Viscount Ridley, whose family estate is Blagdon Hall, near Cramlington, Northumberland. Ridley is married to the neuroscientist Anya Hurlbert and lives in northern England; he has a son and a daughter. He is a great grandson of Sir Edwin Lutyens.

Ridley was non-executive chairman of Northern Rock from 2004 to 2007, earning £300,000 a year, having joined the board in 1994. His father had been chairman for from 1987 to 1992 and sat on the board for 30 years.

In September 2007 Northern Rock became the first British bank since 1878 to suffer a run on its finances at the start of the credit crunch. It was forced to apply to the Bank of England for emergency liquidity funding, following problems caused by the US subprime mortgage crisis. Matt Ridley resigned as chairman in October 2007, having been blamed in parliamentary committee hearings for not recognizing the risks of the bank's financial strategy and thereby "harming the reputation of the British banking industry."

In a 2006 edition of the on-line magazine Edge published by the Edge foundation, Ridley wrote a response to the question "What's your dangerous idea?" which was entitled "Government is the problem not the solution", in which he describes his attitude to government regulation:

In 2007 the environmentalist George Monbiot wrote an article in 'The Guardian' connecting Ridley's libertarian economic philosophy and the £27 billion failure of Northern Rock. In the same newspaper Terence Kealey defended libertarianism, arguing that the performance of the government's regulatory agencies confirmed scepticism about state intervention, because the government had crowded out the market's own regulatory mechanisms.

On 1 June 2010 Monbiot followed up his previous article in the context of Matt Ridley's latest book 'The Rational Optimist'.Ridley has responded to Monbiot on his website, stating "George Monbiot’s recent attack on me in the Guardian is misleading. I do not hate the state. In fact, my views are much more balanced than Monbiot's selective quotations imply." On 19 June 2010 Monbiot countered with another article on the Guardian website, further questioning Ridley's claims and his response.