Rod Stewart really is forever young!

The rock legend — who sparked concern after a string of health setbacks and canceled concerts in June—  belted out a number of hits while dancing on stage at a benefit for Steven Van Zandt’s Teach Rock charity at a luxe mega mansion in Southampton Wednesday night.

A source at the event tells us that Stewart played a “full blown concert” singing favorites like “The First Cut is the Deepest,” “Have I Told You Lately,” and “Forever Young,” for an hour and a half. 

“Everyone was talking about how incredible he looked,” says the spy. “He was dancing all around the stage at 81. He is in better shape than men half his age.”

Another attendee told us, “Rod is doing great— he sounded amazing!”

Stewart told Page Six, “Music gave me my direction when I was a young lad, and I’ve never forgotten it. What Stevie’s built with TeachRock is the real deal — getting music back into classrooms and giving kids that same spark. Sharing a stage with him in Southampton for a cause like this? That’s what it’s all about.”

Stewart recently had fans worried about his health. He canceled a show in San Diego, California June 12 “on the advice of his doctors and following a diagnosis of an acute upper respiratory infection that has resulted in laryngitis,” but angered fans when he was seen cheering at a World Cup match the next day. 

He also postponed his shows at Red Rocks Park and Amphitheatre in Morrison, Colorado, June 16 and 16, citing vocal rest. 

On June 22, he paused his concert in Utah and used an oxygen tank on stage. The altitude may have played a factor. 

He had also previously canceled two Vegas shows in May. 

But it seems like all is well.

A source tells us Stewart played the gig for the charity — which helps keep music in schools — for free.

Van Zandt joined Stewart onstage for performances of “We’re Having a Party” and “Stay With Me.”

The night raised $1.7 million dollars for the charity, which boasts founding members Bono, Jackson Browne, Martin Scorsese, and Bruce Springsteen. 

A dinner with E Street Band member Van Zandt and three other actors from the “Sopranos,” cast in Little Italy was auctioned to two people for $80,000 (combined $160,000) in front of guests including Ramona Singer, Georgina Chapman, Chris and Christina Cuomo, Stefano Tonchi and Fern Mallis.

Stewart will be back on stage at Jones Beach on Friday, July 31.