BARBRA STREISAND’s son has ditched his out-of-control partying thanks to a wildly popular self-help guru – and he made his singing de­but at  mom’s much ballyhooed Brooklyn concert!

Sources say Jason Gould, who’s HIV-positive, has become a follower of the interna­tionally-known author Dr. Wayne Dyer, whose 1976 book “Your Erro­neous Zones” has sold 35 million copies.

Buoyed by his lifestyle change, the 45-year-old joined his superstar mom on stage for a duet during her headline-making “Back to Brooklyn” concert on Oct. 11 in the borough’s new Barclays Center.

“Jason has put his party-boy lifestyle behind him and taken up singing, just like his mom,” said a pal. “He’s found the courage and strength to perform because he’s been following the teachings of Dr. Dyer.”

Jason, whose father is actor Elliott Gould, paid special tribute to his mentor by including an in­spirational quote from Dr. Dyer in the concert program. It said: “Don’t die with your music still inside you…”

As The ENQUIRER recently reported, Bar­bra and Jason patched up their differences for her 70th birthday cel­ebration in April after being estranged for years.

And an eyewitness at the concert said: “When Jason got up on stage with her, you couldn’t have found a mother more proud than Barbra. They sang the duet ‘How Deep Is the Ocean?’ and then Jason belted out ‘This Masquerade’ by himself.

“He’s got a great voice, and Bar­bra was beaming. To have her only son singing with her on stage had to be one of the greatest moments of her life.”