The son of a newspaper editor, he was born in London and educated at Uppingham School in Rutland. At the age of 19 he ventured into the countryside in Hundon, Suffolk to learn about agriculture, and farmed in various locations over the next sixty years, including the rebuilding of a near-derelict smallholding at Redisham, near Beccles.

Out of his early experiences came the book Corduroy, published in 1930. Bell's friend, the author and poet Edmund Blunden, advised him and helped secure his first publishing deal. Corduroy was an immediate best-seller and was followed by two more books on the countryside, Silver Ley in 1931 and The Cherry Tree in 1932, the three books forming a farm trilogy. The popularity of literary back-to-the-land writing in England in the 1930s can be put in the context of, for example, Vita Sackville-West's long narrative poem The Land. The Penguin Books paperback edition of Corduroy came out in 1940 and was much prized by soldiers serving during the Second World War.

Bell wrote the "Countryman’s Notebook" column in the Eastern Daily Press from 1950, and produced over twenty other books on the countryside, including Apple Acre (1942), Sunrise to Sunset (1944), The Budding Morrow (1946), The Flower and the Wheel (1949), Music in the Morning, (1954), A Suffolk Harvest (1956), the autobiographical My Own Master (1961) and The Green Bond (1976).

When The Times started losing circulation to The Daily Telegraph because the latter were running a daily crossword, Bell's father suggested Adrian to the editor as the first 'setter' even though he'd never even solved one. He had just 10 day's notice before his first puzzle was published, in the weekly edition on 2 January 1930. Having set around 5,000 puzzles between 1930 and 1978, Bell is credited with helping to establish its distinctive cryptic clue style.

His son, Martin Bell, is a former BBC war reporter, and was an independent Member of Parliament between 1997 and 2001. Things that Endure, a half-hour BBC radio documentary on Adrian Bell presented by his son, was broadcast on 2 September 2005 on Radio 4. His daughter, Anthea Bell is a translator best known for her translations of the Asterix comics.