In a major boost to the revival of Ground Zero, the glitzy Condé Nast magazine empire has finalized a $2 billion deal with the Port Authority to become the anchor tenant at 1 World Trade Center, sources said yesterday.

Under the groundbreaking 25-year lease agreement, Condé will relocate from 4 Times Square and occupy up to 1 million square feet at 1 WTC (pictured).

As part of the complicated and long-discussed transaction, the Durst Organization will pay $100 million to assume an interest in the 1,776-foot-tall skyscraper and be in charge of leasing the rest of the tower, sources said.

John Bellando, Condé’s chief financial officer and chief operating officer who had been spearheading talks for billionaire Chairman S.I. Newhouse, Jr. said, “We believe that moving to 1 World Trade Center will be a catalyst to help transform downtown similar to our move to Times Square in 1999.”

Condé is not expected to move in until 2015, a spokeswoman said.

But New York officials — after years of delays — are thrilled to announce the deal just months before the 10th anniversary of the Twin Towers attacks.

“Condé Nast is an international franchise and signing them on as an anchor tenant sends a message to the global business community that lower Manhattan is alive, growing and open for business,” said Gov. Cuomo, who oversees the PA.

Added PA Executive Director Chris Ward: “We built a new reality at the World Trade Center and this transaction will be the exclamation point on that turnaround.”

The mag giant and the PA signed a non-binding letter of intent last year — but it took months to hammer out the terms.

A chief demand of Condé negotiators was that its top executives and clients be able to quickly get in and out of the heavily secured site.

Indeed, there will be a provision in the lease that will penalize the PA if it takes too long for honchos to get to their offices, according to a source involved in the negotiations.

Also, the PA has agreed to assume the costs of the last few years of Condé’s lease at 4 Times Square. Durst also operates 4 Times Square.

The deal is to be approved at the next PA board meeting.

Condé has the right to lease 1 million square feet, but can reduce it to 900,000 square feet, sources said.

Tara Stacom’s team at Cushman & Wakefield will continue to work with Durst and the PA to lease the building, sources said.