Hastings was educated at Charterhouse School and University College, Oxford, which he left after a year. He became a foreign correspondent and reported from more than sixty countries and eleven wars for BBC television and for the Evening Standard in London. Hastings was the first journalist to enter the liberated Port Stanley during the Falklands War. After ten years as editor and then editor-in-chief of The Daily Telegraph, he returned to the Evening Standard as editor in 1996 until his retirement in 2001. He received a knighthood in 2002.

He has presented historical documentaries for BBC TV, and is the author of many books, including Bomber Command which earned the Somerset Maugham Award for non-fiction in 1980. Both Overlord and The Battle for the Falklands won the Yorkshire Post Book of the Year Prize.

Hastings lives with his second wife Penny (née Levinson), with whom he had two children, in west Berkshire. In 1999, his 27-year-old son Charles killed himself in Shanghai, China. Hastings dedicated his book Nemesis: The Battle for Japan, 1944-45 to his late son.

He is a Fellow of the Royal Society of Literature and was President of the Campaign to Protect Rural England from 2002-2007.

He currently writes a column for the Daily Mail but often contributes articles to other publications such as The Guardian and The New York Review of Books.

In his 2007 book Nemesis: The Battle for Japan, 1944-45 (also known as Retribution in the United States), the chapter on Australia's role in the last year of the Pacific War was criticised by the Returned and Services League of Australia and one of the historians at the Australian War Memorial for, exaggerating discontent in the Australian Army during this period.

Hastings has supported both the Conservative Party and the Labour Party. He announced his support for the Conservative Party at the 2010 general election, having previously voted for the Labour Party at the 1997 and 2001 general elections. He claimed that "four terms are too many for any government" and described Gordon Brown as "wholly psychologically unfit to be prime minister".