Stephen Fry triumphed over books by Tony Blair and Lord Sugar to win biography of the year at the Galaxy National Book Awards.
He won the prize for his second volume of memoirs, The Fry Chronicles, at a ceremony attended by stars and figures from the publishing world.
Literary veterans Terry Pratchett and Martin Amis were given awards for outstanding achievement.
Popular fiction book of the year went to David Nicholls' One Day.
Pratchett - the Discworld novelist who has been battling Alzheimer's - said of his win: "I'm amazed. You find something that you like doing and do well and keep on doing it and suddenly they give you an award, when all I was really doing was having a lot of fun."
Broadcaster Andrew Marr landed the non-fiction prize for The Making Of Modern Britain, while Hilary Mantel picked up the UK author of the year award, seeing off competition from Maggie O'Farrell and Kate Atkinson.
Yotam Ottolenghi beat Jamie Oliver, Nigella Lawson and Nigel Slater to food and drink book prize for Plenty.
Best children's book was Zog by the creators of The Gruffalo, Julia Donaldson and Axel Scheffler. Their tale about an accident-prone dragon beat comedian David Walliams's book Mr Stink.
American author Jonathan Franzen collected the International Author of the Year trophy for Freedom, while New Writer of the Year went to ceramic artist Edmund de Waal, for his collection of family memoirs, The Hare With Amber Eyes.
The ceremony, which took place at west London's BBC Television Centre, was hosted by David Baddiel with guests including Claudia Winkleman, Arlene Phillips and Richard E Grant.
The public will be invited to vote online for the overall book of the year, with the final result to be announced on 13 December.