He’s buying their silence.

Mayor Bloomberg is taking his most trusted NYPD bodyguards with him to the private sector next year — to ensure they don’t spill any of his secrets, law-enforcement sources told The Post.

“He wants them to go with him because they’ve been with him so long and know him personally,” one source said.

“So, he gives them plum jobs to keep their mouths shut.”

The move means the cops will all hit the jackpot — pocketing cushy pensions and new “six-figure salaries” to keep serving the outgoing mayor, whose eponymous business-media empire has made him the seventh-richest person in America.

Bloomberg’s new security team will comprise a current lieutenant and several detectives, all with more than 20 years on the force. They will file for retirement immediately after mayor-elect Bill de Blasio is sworn in on Jan. 1, sources said.

With public salaries of at least $120,000 each, they’ll all get pensions that amount to at least half that much — on top of their pay to keep working for Bloomberg, sources said.

“They’re all getting six-figure salaries,” one source said.

While Bloomberg’s security detail has 17 members, not all will be riding his gravy-train run.

The unidentified lieutenant who heads the team will land the biggest windfall and “is getting paid a lot more than the detectives,” a source said.

The NYPD provides Bloomberg with ’round-the-clock protection that includes a driver, bodyguard and advance man who secures the mayor’s destination whenever the mayor is out and about.

In 2009, his security team subdued a man who lunged at Bloomberg’s entourage while he was standing on a subway platform.

Previous mayors had police bodyguards who stayed overnight inside Gracie Mansion, but because Bloomberg passed up living there in favor of his plush Upper East Side town house, the NYPD built a security booth outside the East 79th Street pad.

Bloomberg, who also owns a sprawling, waterfront estate in Bermuda, takes members of his security team with him on his frequent, private-jet jaunts to the island getaway.

While the city pays the cops’ wages, Bloomberg has forked over up to $400-a-night for their lodging in a nearby hotel.

He also often treats them to meals with him at his favorite restaurants, including the Port O Call, Rustico and Tom Moore’s Tavern, where a grilled, 16-ounce Porterhouse steak goes for $43 and the catch of the day is $37.

A Bloomberg spokesman declined to discuss the mayor’s plans for his bodyguards, saying: “We don’t comment on security.”

But City Hall sources noted that in the past, ex-mayors including Ed Koch, David Dinkins and Rudy Giuliani were all provided taxpayer-funded NYPD bodyguards after they left office.

In Giuliani’s case, the cost ran nearly $1 million a year, with detectives protecting the ex-mayor along with his mother, Helen; then-estranged wife, Donna Hanover; children Caroline and Andrew; and his then-girlfriend, Judith Nathan.

At the time, Bloomberg defended the expense, noting that Giuliani “took a number of positions that were in the interest of the public, some of which were very controversial, and there are a lot of crazy people out there.”

De Blasio has said he intends to replace Kelly as police commissioner due to Kelly’s unwavering support of the controversial stop-and-frisk crime-fighting tactic.