The son of the journalist Allan Massie, Massie was educated at Glenalmond College in Perthshire and at Trinity College, Dublin, where he edited T.C.D. Miscellany. He was also an active member of the University Philosophical Society, one of the college's main debating societies.
In 1997, he won the John Smith Memorial Mace debating competition, speaking with Matthew Magee and representing the University Philosophical Society. Formerly The Observer Mace, the competition was renamed in 1995 and is run by the English-Speaking Union.
Massie is Scotland Editor of The Spectator, a columnist for the Scottish edition of The Times, and a regular contributor to Border Television as well as BBC Television and radio. Prior to this, he edited a political blog, 'The Debatable Land.'
He was previously Washington correspondent for The Scotsman and Assistant Editor of Scotland on Sunday. He has also written for The Washington Post, Politico, The Daily Telegraph, The New Republic, Foreign Policy, The Sunday Times, The Daily Beast, the Los Angeles Times, The Scottish Daily Mail, National Review Online, The Sunday Telegraph, The New York Times,The American Conservative, TIME magazine, Bloomberg Businessweek, The Observer, the New Statesman, The Big Issue, Slate, CapX, the Irish Independent, Newsweek and The Sunday Business Post. Since January 2009 he has written a blog that is published by The Spectator. In 2012 he was short-listed in the blog section for the Orwell Prize for political writing.
In November 2018 Alex Massie wrote a piece for The Spectator arguing that France should honour Nazi collaborator Philippe Pétain. He wrote the book reviews for the 2020 edition of Wisden Cricketers' Almanack. In May 2020 Massie wrote two articles for The Spectator; the first on 'Why Dominic Cummings must go,' engaged with the row over a road excursion from London to Durham, and then Barnard Castle by the PM's adviser, during the coronavirus lockdown.