Johnson became a member of the Cambridge University Wine and Food Society while an undergraduate at King's College, Cambridge in the 1950s, while reading English. On describing his introduction to wine-tasting Johnson has recalled:

[Adrian Cowell, founder of the International Wine & Food Society] came in after dinner with two glasses and said, "Come on, Hugh, are they the same? Or different?" Both were, I am sure, red Burgundy, but one was magic and one was ordinary. This caught my imagination. It was my Damascene moment.

Johnson has been writing about wine since 1960, was taken on as a feature writer for Condé Nast Publications upon graduation, and early worked with magazines such as Vogue and House & Garden. He has published a wide array of books, starting with the publication of Wine in 1966 at a period he became the wine columnist of The Sunday Times.The publication of The World Atlas of Wine in 1971, considered the first serious attempt to map the world's wine regions, became described by the sitting director of the INAO as "a major event in wine literature".

Over the years he has held the position as director of Château Latour, is the co-founder and a partner in The Royal Tokaji Company, and in 1986 founded the Hugh Johnson Collection Ltd. which sells stemware and other artefacts related to wine. Johnson is also a Horticulturalist with a special interest in trees, and has published a standard guide to gardening, The Principles of Gardening. Since 2004 Johnson has acted as editorial adviser to The World of Fine Wine magazine.

He was selected the Decanter "Man of the Year" in 1995, and was awarded the Officer of the British Empire distinction in 2007.

Johnson is known as one of the wine world's most vocal opponents to awarding numerical scores to wine. In the autobiography A Life Uncorked, Johnson also expressed regret over the wine critic Robert Parker's influence on the world of wine, which has in his view moved winemaking in many regions towards a more uniform, bigger and richer style. In 2005 Johnson stated, "Imperial hegemony lives in Washington and the dictator of taste in Baltimore".

• Wine (1966)
• The World Atlas of Wine (1971, several editions; since 2004 co-authored with Jancis Robinson)
• The International Book of Trees (1973)
• Hugh Johnson's Pocket Wine Book (1977, since published annually)
• The Principles of Gardening (1979), Mitchell Beazley Publishers (U.K.)/Simon & Schuster, Inc. (U.S.)
• Hugh Johnson's Wine Companion (1983, several editions)
• The Story of Wine (1989)
• The Art and Science of Wine: The Subtle Artistry and Sophisticated Science of the Winemaker, (1992, co-authored with James Halliday)
• A Life Uncorked (2006, autobiography, anecdotes and opinions)
• Hugh Johnson's Pocket Wine Book 2011 (2010, wine guide)
• Hugh Johnson's Wine Guide 2011, iPhone app (2010, wine guide on iPhone)

Television

• Vintage: A History of Wine (1989)