Josh Flagg is leveling up his East Coast game — he’s in escrow on a $10 million Hamptons estate … TMZ has learned.

Real estate sources tell us the real estate power broker and his childhood friend Justin Gruenberg are in escrow on a nearly $10 million estate in the ultra-exclusive Georgica Estates section of East Hampton, NY.

This marks Flagg’s second major East Coast move this year as he continues building his real estate empire. He already owns two homes in Beverly Hills — including one that was asking $11 million from Charlie Puth — along with properties in Miami and New York City.

The home features 6 bedrooms, 6 full baths, and over 6,800 square feet of indoor/outdoor living space. It’s loaded with Wolf and Sub-Zero appliances, and the open-concept living room flows into a 700-square-foot-plus covered porch through 38-foot accordion doors — complete with an outdoor fireplace and built-in BBQ.

Out back, there’s a heated pool, in-pool sundeck, built-in spa, and a pool house with an outdoor shower and attached garage.

We reached out to Flagg and Gruenberg … so far, no word back.