Gago was born in Newcastle, England, where he lived until the age of six before emigrating to Australia, settling in Melbourne. He became a high school teacher of mathematics and chemistry in the early 1980s after graduating from the University of Melbourne with a Bachelor of Science. At age twenty-nine, he undertook a Bachelor of Applied Science (Oenology) degree at Roseworthy College, graduating as dux.
Gago started a job with Penfolds Wines in 1989, initially producing sparkling wine before moving on to reds, and eventually being made Penfolds Red Wine Oenologist. Gago succeeded John Duval as Penfolds Chief Winemaker in 2002, becoming only the fourth person to hold the position since Max Schubert was first appointed in 1948. Gago has been involved with the market promotion of Penfolds wines since the early 1990s, travelling extensively to attend wine shows and conduct tastings and master classes.
On winemaking, he has said, "I would not say that my style is particularly evident in the winemaking, although I'm a firm believer in no filtration or fining, natural yeast, open-top fermenting and other noninvasive techniques. For me, it's about knowing when to interfere and when to stay out of the way".
Gago was named 2005 Winemaker of the Year by Wine Enthusiast Magazine. He was named 2012 Winemakers’ Winemaker of the Year by Institute of Masters of Wine and international trade publication The Drinks Business.
- Discovering Australian Wine : A Taster's Guide (1995), ISBN 0-646-22238-4
- Australian Wine : From the Vine to the Glass (1997), ISBN 0-646-31855-1
- Australian Wine : Styles and Tastes (2002), ISBN 0-9581605-0-3
The books were co-authored with Patrick Iland.
- Penfolds Grange Guide: Langtons
- The Definitive Penfolds Grange Guide: Langtons
- Peter Gago, Penfolds Chief Winemaker: Penfolds Wines
- Peter and Gail Gago - South Australia's power couple: The Advertiser 21 June 2013
- Past chief winemakers: Penfolds wines
- Penfolds Winemaker Named Wine Enthusiast Winemaker of the Year: BusinessWire 24 January 2006
- Peter Gago Named as Winemakers' Winemaker in 2012: Masters of Wine 5 March 2012
- SA winemaker Peter Gago named world's best winemaker: The Advertiser 6 March 2012
- Iland, Gago, Caillard and Dry. "A Taste of the World of Wine". Patrick Iland Wine Promotions Pty Ltd.
- "Peter Gago : Winemaker : Winemaking Philosophy : Winemaking". Retrieved 2006-04-26.
- Faulkner, Jane (2003-12-15). "Like a kid in a lolly shop". The Age. Fairfax. Retrieved 2006-04-21.
- Schachner, Michael (2005-12-15). "Winemaker of the Year - Peter Gago". Wine Enthusiast Magazine. Retrieved 2006-04-26.
- "Max Schubert : Winemaker : Winemaking Philosophy : Winemaking". Retrieved 2006-04-26.
- Plane, Terry (2002-07-25). "Penfolds' new chief to be top of the Grange". The Australian. News Corp.
- "Southcorp Announces Peter Gago's Appointment as Penfolds Chief Winemaker, Assuming the Mantle from John Duval" (Press release). Southcorp Wines. 2002-07-24.