Ben Dunne said that he will close his doors to customers until a vaccine or effective treatment for Covid-19 is found.
The Irish businessman said that he could conceivably see himself having to lay off his 80 staff rather than see people using his facilities die from Covid-19.
Under Phase Three of the Government's Roadmap to Reopening Businnes and Society, gyms have been allowed to open since June 29.
Speaking on RTE's Today with Sarah McInerney, the 71-year-old said that gyms are not a safe place during the pandemic.
"I'm not reopening my gyms because it is not safe to do so and until is safe I don't believe in putting a product of facility in front of the consumer," he said.
"I have to put rules and regulations in my business and I have to make sure that they are kept. It's a laugh the way the regulations are being followed. If you go into a shop people are not keeping distance and masks are mandatory but they're not being worn.
"I am only looking after my business and until I can keep my place safe, that the virus is under control and treatable or with a vaccine, I am not opening up my business. I don't believe that gyms are a safe place for people at the moment."
Mr Dunne who employs 80 staff in his ten 'Ben Dunne Gyms', said that he can conceivably see himself 'going bust' and having to lay off his staff as a result of the virus.
"I am fully convinced that this virus is not under control. We don't even know when or how it started and we are putting in place very stringent rule and regulations to try keep in under control in the country," he said,
"It's impossible to keep people apart, to make people wash their hands often enough, to stop people talking each other - to keep their distance.
"I think we're heading for a deep, deep depression. My staff will be out of a job and I'll go bust, but I'd rather go bust than be burying people who are using my facilities when I knew they weren't safe.
"It's a possibility. It's facing me as plain as the nose on my face and it's facing other people as well but they don't want to say it as openly as I do. This thing is going to devastate our country and many other countries, unless we get int he right people. It can be fixed.
"I wouldn't dare to open. We're all in it together and if we keep going the way we are, we'll all go down together."
The Covid-19 message is getting very confusing. On the one hand there are dire warnings about the rising R number. Yet at the same time it will be a case of "bon voyage" to holidaymakers from Ireland flying to a "green list" European country from next week.