Born in Hampstead, London and brought up in Gloucestershire, Fearnley-Whittingstall was educated at Eton College and St. Peter's College, Oxford, where he read Economics.

After graduating from university, he began a career in conservation work in Africa. He then spent a brief period as a sous-chef at River Café. Fearnley-Whittingstall says "being messy" and "lacking discipline" made him unsuited to working in the River Café kitchen. He regards it as an event that helped shape his current career.

He became a freelance journalist, published in Punch, the Evening Standard and The Sunday Times. In 1994 Macmillan published his Cuisine Bon Marché, which contained recipes and guidance on a wide range of food commonly found in British markets.

He is married to Marie and has two sons (Oscar and Freddy) and an adopted daughter (Chloe who goes to Queen's College, Taunton ). His wife has recently had another baby. They live on 37.19 acre Park Farm near Uplyme, close to the Dorset-Devon border.

Hugh Fearnley-Whittingstall was voted "man of the year" in the Whickham lifestyle competition in 2007 and 2008. After a vote in early January 2009 he became the first person to win this award three years in a row.

His mother is gardener and writer Jane Fearnley-Whittingstall. His father is Robert Fearnley-Whittingstall.

On television, Fearnley-Whittingstall's reputation is that of an eccentric chef. Initial exposure came in Cook on the Wild Side, an exploration of earthy cuisine. His habit of "picking up roadkill and eating the hedgerows [...] earned him his nickname of Hugh Fearlessly-Eatsitall". He followed this with the series TV Dinners, during an episode of which he notoriously flambéed and puréed a human placenta which was served as a pâté and "much enjoyed by the baby's family and friends".

In 1997 he moved into River Cottage, a former game-keeper's lodge in the grounds of Slape Manor in Netherbury, Dorset, which he had previously used as a weekend and holiday home. This became the setting for three Channel 4 series: Escape to River Cottage, Return to River Cottage and River Cottage Forever (directed by Garry John Hughes). He has since bought a farm in Thorncombe, Dorset, with his family. Through his experiences on these programmes, in which he had to produce everything himself in The Good Life style, he has become a keen supporter of the organic movement. Beyond River Cottage followed Fearnley-Whittingstall's progress as he set up a new business, River Cottage H.Q., close to Dottery (near Bridport), Dorset. In 2002 he presented the six-episode series Treats from the Edwardian Country House. In 2005, a series called The View from River Cottage was produced using extracts from the four previous series, accompanied by newly-recorded narration. This was followed by The River Cottage Road Trip, consisting of two brand new one-hour shows. 2005 also saw Fearnley-Whittingstall appear on the first series of Channel 4's The F Word, advising Gordon Ramsay on the rearing of turkeys at his London home. These were subsequently eaten in the last episode of the series. Further appearances on The F-Word in 2006 and 2007 involved Fearnley-Whittingstall advising Ramsay on the rearing of pigs and lambs respectively, again with their being eaten in the last episodes of the series.

During 2006 Fearnley-Whittingstall moved River Cottage H.Q. from the original rented and converted barn near Bridport, to its new premises, Park Farm, a farm near to Uplyme on the West Dorset/East Devon border. A new series called The River Cottage Treatment was filmed there and was broadcast on Channel 4 in November 2006.

In 2007, Fearnley-Whittingstall presented the short series River Cottage: Gone Fishing, which examined some of the lesser-known fish to be caught around the British Isles.

At the start of 2008, Fearnley-Whittingstall — along with fellow celebrity chefs Jamie Oliver and Gordon Ramsay — was featured in Channel 4's Big Food Fight season. His contribution to the season was Hugh's Chicken Run, shown over three consecutive nights, in which he created three chicken farms in Axminster (one intensive, one commercial free range, and a community farm project staffed by volunteers), culminating in a "Chicken Out!" campaign to encourage the eating of free-range chicken.

Fearnley-Whittingstall most recently presented a magazine-style food programme produced at River Cottage HQ, River Cottage Spring, which ran from 28 May to 25 June 2008 on Channel 4, and was followed later that year by River Cottage Autumn, which ran from 16 October to 6 November. He was a guest on BBC Radio 4's Desert Island Discs on 31 July 2009.

He is a permanent team captain (opposing a different guest captain each week) on a food-based panel game, The Big Food Fight (not to be confused with the earlier project of the same name) which began on Channel 4 on 8 September 2009.

On November 12 2009 a new series of four River Cottage episodes started at 8pm on Channel 4, titled 'River Cottage - Winter's on the Way'.

Fearnley-Whittingstall has presented three one-hour shows detailing how commercial breeds of broiler chickens are reared for their meat in just 39 days. This compares to slow growing breeds which live for at least 75 days in more humane and natural surroundings. Fearnley-Whittingstall is currently trying to encourage people to become more aware of food production issues through his "Chicken Out" campaign.

As part of the campaign, Fearnley-Whittingstall singled out Tesco as a major retailer of chickens which failed to conform to the standards laid down by the Farm Animal Welfare Council in its "Five Freedoms" concept. As a result, he purchased a share in Tesco so that he could take advantage of a procedure set out in section 338 Companies Act 2006, which entitles any shareholder of a company to table a resolution at a general meeting of a company provided he can garner a certain level of support from other shareholders. Fearnley-Whittingstall managed to find sufficient shareholders to support the tabling of a resolution at Tesco's AGM on 27 June 2008, which, if passed, would have committed Tesco, within a reasonable timeframe, to take appropriate measures to ensure that chickens purchased for sale were produced in systems capable of providing the "Five Freedoms". An insufficient number of shareholders voted in favour of the resolution for it to be passed.

In an interview in January 2008, Fearnley-Whittingstall extended the call to hospitality and food service operators:

“It’s one thing to challenge individual consumers to give up intensively reared chicken but it’s also an issue where anyone in the business of selling chicken has to take a stand... in some cases I know chefs, not naming names, at the very high-end sector who are not using free-range birds. Some of them are on the road to Michelin stars.”

He has helped develop Stinger, a nettle-flavoured ale, with the Hall and Woodhouse brewery.

Fearnley-Whittingstall's most recent project was the conversion of an old inn in Axminster to an organic produce shop and canteen which opened in September 2007.

In 2009, Hugh became a patron of ChildHope UK, an international child protection charity working in Africa, Asia and South America.

In 2009 The River Cottage Summer's Here programme promoted the land share project which seeks to bring together people who wish to grow fruit and vegetables but have no land with landowners willing to donate spare land for cultivation,

Fearnley-Whittingstall has also written the best-selling cookery books The River Cottage Cookbook, The River Cottage Year and The River Cottage Meat Book (including award-winning photography by Simon Wheeler), which details his philosophy of organic husbandry whilst also covering many aspects of selecting, preparing and cooking meat, and The River Cottage Fish Book. His latest book, published on 5 October 2009, is River Cottage Every Day. He has written articles for The Guardian and The Observer since 2001. A collection of his short articles was published in October 2006 under the title Hugh Fearlessly Eats It All: Dispatches from the Gastronomic Frontline. He also forwarded the Bumper Book of Un-useless Japanese Inventions written by Kenji Kawakami.