Aslet was educated at King's College School in Wimbledon and Peterhouse, Cambridge, where he earned a degree in the history of architecture.
After 13 years as editor-in-chief, from 13 March 2006, Aslet left and took on a newly created role of editor-at-large, which allowed him to write more books as well as articles for newspapers such as The Daily Telegraph, the Daily Mail, and The Sunday Times.
He has regularly broadcast on radio and television current affairs programmes including Newsnight.
In 2019, he established the publishing imprint Triglyph Books with the photographer Dylan Thomas.
Two years later he was one of the small team that founded the Ax:son Johnson Centre for the Study of Classical Architecture at Downing College, Cambridge.