Sports guru Brandon Steiner, who lost control of his eponymous collectibles company this summer, is back in the game, The Post has learned.

The 60-year-old entrepreneur and founder of Steiner Sports Memorabilia — which famously inked a deal with the Yankees in 2009 to sell fixtures from the old stadium, including seats — plans to launch CollectibleXchange.com this week, he told The Post.

The new site will offer many of the same collectibles for which Steiner became famous in his 32 years running Steiner Sports, but it will operate more like online auction site eBay. Instead of selling autographed baseballs and signed jerseys directly, the site will link buyers with sellers, including athletes who want to offer their game-worn helmets and other gear directly to collectors.

The site was to launch with some 10,000 items, including an autographed Wayne Gretzky hockey jersey for $10,114; a baseball signed in the 1940s by New York Yankees legend Joe DiMaggio for $808; and a Texas A&M football helmet signed by 2012 Heisman Trophy winner Johnny Manziel, valued at $649.

CollectibleXchange takes a 20 percent commission for whatever is sold on the site and charges an additional fee for authenticating merchandise.

As The Post reported exclusively in June, Steiner was blindsided by the sale of his company’s inventory to licensed sports apparel maker Fanatics. Steiner was still running Steiner Sports as chief executive after selling it to Omnicom in 2000 for $25 million. He was informed Fanatics had bought the inventory and intellectual property from Omnicom on May 31 after leaving the office for a Yankees-Red Sox game, The Post reported.

To this day, he doesn’t know who owns the Steiner Sports brand.

“I don’t know if Fanatics bought my name or Omnicom still owns it,” Steiner conceded, speaking publicly for the first time since his company was sold for parts. “But I’m not involved in Steiner Sports anymore and it’s a weird thing to even say. I’m proud of the Steiner Sports name.”

In addition to CollectibleXchange.com, the Brooklyn native recently launched Steiner Agency, which connects athletes with firms that want to hire them for promotional events.