This seller sure hopes to clean up.

Joy Mangano, the famed creator of the Miracle Mop, has slashed the price of her North Shore, Long Island, estate to $15.75 million — down from $20 million following a broker swap.

Known as Swan Manor, the property at 1 Swan Place in St. James was built in 1917 and sits on a sprawling 9 acres. The gated spread — inspired by the Gilded Age architect Stanford White — is now decked out in soothing tones of cream and beige.

The offering also comes with a three-bedroom barn-turned-guest house that was, briefly, home to Robert De Niro. The actor stayed there when filming a 2015 biopic called “Joy,” starring Jennifer Lawrence as Mangano, with De Niro playing her father. 

At 22,000 square feet, the three-residence property — there are also staff quarters — comes with a whopping 14 bedrooms and 14½ baths.

Mangano, an inventor and entrepreneur who is currently the CEO of CleanBoss and executive producer of USA Network’s “America’s Big Deal,” bought the home for $1.35 million in 2000 and put “millions” into the renovations. She is now downsizing.

The smart-wired main house’s design details include a formal dining room, a chef’s kitchen and a great room with high ceilings and window walls. There’s also an indoor pool with a hot tub, a gym, a sauna and a wine cellar with a tasting room.

The grounds, with seasonal water views of Stony Brook Harbor, include landscaped gardens, a tennis/pickle ball court, imported porcelain patios, a pergola deck, a stone garden waterfall, walkways, a bluestone driveway, a separate four-car garage and a security system.

The listing, from broker Maria Orlandi of Compass, touts the property as a “Hamptons alternative.”

Indeed, St. James has its own history as a celeb vacation spot for prior generations of talent including John Barrymore, Myrna Loy and Irving Berlin.