The Seven Barrows handler has now secured six victories in the two-mile showpiece.
Just for good measure, Henderson also saddled runner-up My Tent Or Yours, who was finishing second in the race for a third time.
Jockey Noel Fehily said of the 5-1 winner: "Early on I felt I was doing too much and I thought it took me a while to get him switched off.
"He's just a very good horse. It's just fantastic. It was a great performance."
The first two horses home are owned by JP McManus, with four and a half lengths the winning distance. Petit Mouchoir was third after cutting out much of the running.
Buveur D'Air was sleek and assured in his jumping as Fehily and his companion glided into the lead before the last flight.
My Tent Or Yours deserves fulsome praise at the grand old age of 10, but Aidan Coleman's partner never looked a genuine threat to the winner.
Buveur D'Air is now unbeaten in four starts this season, but he began the campaign over fences.
However, Henderson and McManus made the decision to revert to hurdling, with his facile victory at Sandown in February a sign of things to come.
Petit Mouchoir was another three lengths away from the winner.