Jeal's mother was Norah Pasley, daughter of Sir Thomas Pasley Bt, and Constance Wilmot Annie Hastings, who was the daughter of the 13th Earl of Huntingdon. Jeal was educated at Westminster School, London, and Christ Church, Oxford. From 1966 to 1970, he worked for BBC Television in the features group. For his third novel, Cushing's Crusade, he was awarded the John Llewellyn Rhys Prize in 1975. Jeal is the parent, with his wife Joyce Jeal, of three daughters.

Jeal has been writing books since the 1960s, for London-based publishers. Although most of his works are fictional, he is best known for his biographies, all of which fundamentally and enduringly changed the way in which his subjects had hitherto been perceived. His new biography of Stanley has attracted interest for its revisionist tendencies. Dr Jane Ridley in the Sunday Telegraph (2007-03-18) argues that 'Tim Jeal's absorbing biography will surely be definitive.' Professor John Carey in the Sunday Times (2007-03-18) accepted that Jeal's 'ardent, intricate defence of a man history has damned' had been successful,and concluded: 'Anyone who, after reading this book, imagines they would have behaved better than Stanley, if faced with the same dangers, must have a vivid imagination.' Tim Gardam in the Observer (2007-04-01) felt that Jeal had 'fulfilled a mission to rehabilitate one of the most complex heroes of Victorian Britain'. Kevin Rushby in the Guardian (2007-03-24), said he was 'aware of the dangers of revisionism' and doubted that Stanley was as innocent as Jeal argued, but pronounced Stanley 'a stunning and provocative work, an awesome piece of scholarship executed with page-turning brio.' In the Washington Post (2007-12-23), Jason Roberts wrote of '...this commanding, definitive biography' being 'an unalloyed triumph...', and in the New York Times Book Review (2007-09-30), Paul Theroux described it as 'the most felicitous, the best informed, the most complete and readable [biography of Stanley]'. Tim Jeal had unique access to the massive Stanley collection in the Royal Museum of Central Africa in Brussels and saw many letters, diaries and other documents (including correspondence between Stanley and King Leopold of Belgium) unseen by previous biographers. Stanley was named Sunday Times Biography of the Year for 2007 (2007-11-25) and won the American National Book Critics Circle Award for Biography (2008-03-06)

Novels

• For Love or Money (1967)
• Somewhere Beyond Reproach (1968)
• Cushing's Crusade (1974)
• Until the Colours Fade (1976)
• A Marriage of Convenience (1979)
• Carnforth's Creation (1983)
• For God and Glory (1996)
• The Missionary's Wife (1997)
• Deep Water (2000)

Biographies

• Livingstone (1973) (about David Livingstone)
• Baden-Powell (1989) (about Robert Baden-Powell)
• Swimming with My Father (2004) (memoir)
• Stanley: The Impossible Life of Africa's Greatest Explorer (2007) (about Henry Morton Stanley)