The 29-year-old Harden joins an ownership group led by Gabriel Brener, who purchased the majority share of the business in December 2015.
"We are thrilled to welcome James into our club. He’s an icon in the Houston community, and not only is he a great basketball player, he has an extremely smart and savvy mind for business," Brener said in a statement. "James will bring a very unique perspective to our ownership group, and I’m looking forward to hearing his thoughts and opinions on the club going forward."
Harden, the NBA’s MVP in 2018, has earned first-team All-NBA honours in five of the past six seasons.
"Houston is my home now and I saw this as a way to invest in my city and expand my business interests at the same time," Harden said. "Soccer in general, and especially MLS, have exploded in this country throughout my lifetime.
"I’ve been a fan of the game for several years, and I know that Houston has a massive soccer fan base, so it was an easy decision for me when this opportunity arose."
Harden joins a Houston ownership group that includes former boxer Oscar De La Hoya. Others in the ownership group are Ben Guill, managing partner of White Deer Energy, a Houston-based energy private equity fund, and Jake Silverstein, a private investor based in Portland.
Haden’s business portfolio already includes interests in the sports drink BodyArmor, Art of Sport (A.O.S.), a body- and skin-care brand tailored specifically for athletes, and the sock company Stance.
The Houston Dynamo visit Toronto FC in MLS action Saturday.