The fair attracts up to 100,000 visitors each year and is the oldest and largest event of its kind in Europe.
Discussion had been held regarding holding a limited form of the event but it has now been officially cancelled outright. The decision came following meetings held between Galway County Council and the festival committee, along with Gardaí and health officials.
It was decided that it would be impossible to control crowds and maintain social distancing, and so could not go ahead while the virus is still spreading.
Organisers will now look ahead to next year's event, which will mark the 300th anniversary of the fair.
In a further blow to equine enthusiasts, this year's Galway Races will be limited to just 1,000 spectators per day, just 2% of Galway Racecourse's capacity.
Just one thousand spectators can attend each day of the Galway Races seven-day summer festival, which goes to post on Monday, July 26.
Chief Executive of Galway Racecourse Michael Moloney expressed his disappointment at the news.
"We were hoping for more," he said. "It’s just over 2% of our capacity and we see other sporting venues around the country this weekend are heading well into the twenties in terms of percentage capacity."
