NEW YORK — Restaurateur Danny Meyer will soon require diners to be fully vaccinated if they want to dine indoors at one of their full service restaurants.

The new policy goes into effect on Sept. 7.

Along with requiring employees to be vaccinated, Union Square Hospitality Group will also require indoor diners at its full service restaurants like Union Square Cafe, The Modern and Gramercy Tavern to show proof of vaccination.

Meyer, who is also the founder of Shake Shack, said in a CNBC interview that a decision will come later on whether the mandate will also apply to the fast-food chain.

Mayor Bill de Blasio applauded Meyer’s move in a press briefing Thursday, calling it a "huge moment."

The mayor said the public sector took its “first bold step” with its vaccine or test mandate, and encouraged the private sector to explore that and more.

“My message to the private sector is, different organizations have different opportunities to do things. Private entities do have more flexibility in some cases,” de Blasio said.

“’Go as far as you can go.’ That’s what I said, and look, here’s Danny doing it. We talked to him about it as he was preparing, encouraged and supported him,” the mayor said.

Meyer in April was named head of the city's Economic Development Corporation and is leading the city's efforts to move out of the pandemic.

Along with Clive Davis, he's producing the “WE LOVE NYC: The Homecoming Concert” in Central Park on Aug. 21.