Hearn, World Snooker's chairman, has suggested that O'Sullivan should know better than to be so critical.
The five-time world champion argued that snooker is a "nothing-type sport".
Ronnie's latest comments are off the scale, even for him
Hearn told BBC Radio 5 live: "The game of snooker has never been in a stronger position. Prize money has trebled in the last five years."
On Monday, O'Sullivan said that, in order for it to thrive, snooker needs to embrace a more corporate image, similar to sports such as golf, tennis and Formula 1.
He also questioned the levels of prize money available to players, adding that the sport struggled to attract enough lucrative sponsorship.
The total prize money available on the tour this season has reached £10m for the first time as part of Hearn's revamp of the sport.
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Hearn, speaking on Tuesday, said: "Ronnie's a massive name. He lives on another planet sometimes, but he's a massive draw and a great asset to the game. His latest comments are off the scale, even for him.
"There are many, many sports that would cut their arm off to be in the position that snooker's in. We're on an upward trend.
"In terms of prize money, there was a time, maybe five or six years ago, where we spent 10 years in the doldrums, there's no question about it.
"The game has rebuilt and is going from strength to strength, particularly in China, Europe, and obviously within the UK."
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Snooker is in a better state than it has ever been despite Ronnie O'Sullivan's suggestion that the sport is a "car boot sale", Barry Hearn says.