Mayor Bill de Blasio plans on leaving Gracie Mansion true to form: late!

Movers were at the mayor’s official residence on Friday to pack de Blasio’s stuff into a pair of vans, but City Hall said the perpetually tardy bureaucrat would remain there overnight, even though Mayor-elect Eric Adams succeeds him immediately after the stroke of midnight.

With one of de Blasio’s two Park Slope houses rented out and the other undergoing extensive remodeling, sources said he would be relocating to the Marriott hotel in downtown Brooklyn.

It’s unclear how long de Blasio plans to stay there. It was not clear who is paying for the hotel stay.

And even though he could have declined it, law enforcement sources also said that taxpayers will continue to pick up the tab for de Blasio to be protected by an NYPD security detail for at least six months.

The unit will comprise a sergeant and six detectives, down from the inspector, lieutenant, three sergeants and about 30 detectives now assigned to the outgoing mayor and his family, sources said.

“He needs the detail since he doesn’t own a car and even though he put in all those bike lanes, he is not about to ride on a bike through the city,” one source said.

“He would be too easy a target for the thousands of New Yorkers who hate him to verbally harass him or worse.”

In October, de Blasio landed in hot water after a Department of Investigation probe found he used his NYPD security detail for “political purposes” during his failed presidential campaign and to run personal “errands” for Hizzoner — including helping his daughter move and chauffeuring his son — throughout his mayoralty.

The 49-page Department of Investigation probe undercut years of explanations from de Blasio — that his family’s safety necessitated detail assignments — by revealing the NYPD never produced written assessments of those threats and that assignments were driven by the preferences of de Blasio’s family.

Outside Gracie Mansion Friday, de Blasio’s soon-to-be-former neighbors on Manhattan’s Upper East Side were overjoyed today to see him finally packing up and preparing to leave.

“Please get him out of here! I can’t wait,” one woman yelled at the movers as she passed by the entrance on East End Ave.

Another woman shouted, “He can’t leave soon enough!” and a third — who was powerwalking along barricades that blocked the sidewalk — bitterly cursed de Blasio under her breath.

“F–king a–hole mayor,” she muttered.

One East End Avenue resident told The Post, “I’ve lived here for 30 years and he’s the biggest loser I’ve ever called my neighbor.”

“He ruined the city,” the man railed.

“The filth, the crime, the homelessness. I’ve never been so happy to see a neighbor move out.”

De Blasio infamously had a white privacy fence erected around the historic mansion to shield him as he sat on the porch, The Post revealed in December 2014 — about six months after his delayed move there following his election in 2013

At the time, a source said that de Blasio “felt like people were getting too close to him” because some “would see him and yell, ‘Hi, Mr. Mayor!’”

Neighborhood podiatrist Sam Carr, 61, used his Friday lunch break to stand outside Gracie Mansion with a sign that bid de Blasio “Good Riddance!!” and warned: “Don’t let the door hit your ‘toochas’ on the way out!”

“I really care about New York and it’s just so sad to see the destruction over the past eight years,” Carr said.

“We’re like the Wild Wild West now thanks to him. So, I said: What the heck? I’m right around the corner from Gracie Mansion. It’s his last day. Let me give him a proper send-off.”

Workers in stores along nearby York Avenue said de Blasio — who made a habit of riding to Park Slope in a convoy of SUVs for leisurely morning workouts at the Prospect Park YMCA and breakfasts at Colson Patisserie — wasn’t among their customers.

“I can’t say I’ll miss him because he never once bought anything here,” said a worker at the Millennium Convenience & Grocery store.

“He lived here but this was never his neighborhood.”

Kay Qu, manager of the Park East Wines and Spirits store, said, “He’s lived a block away all this time, but I never once sold him any wine.”

“I knew he lived nearby, but that’s about it,” Qu added.

A waitress at Effy’s Cafe also said, “I never saw him or his wife eat here.”

“Local people like to come here but I don’t think they considered themselves local, really,” she said.

“So, what’s to say goodbye to?”

The Post saw one of the moving vans haul several boxes of de Blasio’s possessions to a U-Haul moving and storage facility in Park Slope.

De Blasio’s press secretary, Danielle Filson, declined to elaborate on his plans beyond saying, “The mayor has said repeatedly he’s moving back to Brooklyn, and that’s exactly what he is doing.”

In regard to his security detail, she added, “With every outgoing mayor, NYPD conducts a risk assessment and makes a decision based on that.”