Saward was educated at Haileybury College and attained a degree in history at Bedford College, University of London. In 1984 he joined Autosport magazine in London. He began reporting on Formula One in 1988, working alongside Nigel Roebuck and remained as Grand Prix Editor of Autosport until 1993. He later wrote for the F1 News magazine, and went on to create the Business of Motorsport newsletter and grandprix.com, a Formula One website. This was followed by a blog and the launch of GrandPrix+, an e-magazine developed in partnership with David Tremayne. Saward also hosts audiences for Formula 1 fans who can ask questions about the sport. He also features in An Aside With Joe podcasts at Sidepodcast. He has the distinction of attending all the F1 races since 1988, is accredited as an FIA Formula 1 Permanent Passholder and has previously sat on the board of Caterham Cars as a director.  He is also the F1 Editor of Autocar magazine.
Saward has also authored a number of books, including The World Atlas of Motor Racing. In 2007 Saward published The Grand Prix Saboteurs, detailing the story of racing drivers who went on to establish a sabotage network in France during World War II. As a result of this book, the Guild of Motoring Writers named Saward the Renault UK Author of the Year. He has also published a biography of his great-grandfather, Henry George Kendall, called The Man who Caught Crippen.