Speaking to the Indianapolis Star, Harrington said he started looking into cannabis around a decade ago to deal with the 14 surgeries he had during his playing career.
He now employs more than 70 people in four states with plans to expand his business to seven states in America by the end of the year.
Harrington believes the company could be listed at a $US1 billion ($AUD1.4 billion) valuation if he put it up for sale on the open market, but he insists he doesn't care about the money.
"At the end of the day, I'm not doing it for the money," Harrington told the newspaper. "Money will come and go, but I'm more focused on service and products and patients. If we take care of them, the money will be there."
When Harrington first wanted to invest in a cannabis company, he went in with his cousin.
The long-time NBA star invested $5 million but under his cousin's name so the NBA wouldn't find out.
With the changing tide in the US on the back of the opioid epidemic — which has seen increased cases of people becoming addicted to painkillers — Harrington hopes cannabinoids will soon be an alternative for athletes.
"I firmly believe that (medical marijuana) will be allowed in one of these major sports leagues in the next two years," Harrington told The Star.
"Leagues say health and safety is first. If that's the case, stop prescribing opioids and giving prescription pills and shooting these NFL players up to be able to go compete. They walk away from the game and their quality of life sucks and if cannabis can help them and give them quality of life, they should look into it."
With his hope of a $1 billion buyout for his company, Harrington said he's uniquely placed to join the likes of Michael Jordan, Tiger Woods, Arnold Palmer, Jack Nicklaus and Michael Schumacher in the billionaire sportsperson club.
Being a professional athlete banking healthy pay cheques made the leap into his business venture easier, because it's an expensive industry to get into with the cost of growing and acquiring licences able to soar upwards of $10 million just to be able to start out.
"If you're new to the space, you're going to mess up," Harrington said on Points on the Board.
"I messed up a lot when I first started but I was a professional athlete and I could cover the mistakes. But a lot of people … don't have that opportunity.
"One thing I'm very passionate about is trying to create avenues for people of colour to be able to participate in the cannabis industry."
