Macy’s just scored its biggest exclusive since nabbing Tommy Hilfiger in 2008.

Looking to prop up sagging sales, Macy’s will become the only department store to sell DKNY women’s apparel and accessories as of next year.

Macy’s announced the exclusive distribution deal on Monday with G-III Apparel Group, a New York manufacturer that bought the brand last year from French luxury giant LVMH.

“Macy’s gets a product that won’t be sold at Amazon, but it also takes DKNY more down-market,” said Wunderlich analyst Eric Beder, predicting DKNY jeans, shoes and bags will be discounted by as much as 40 percent.

Donna Karan’s more affordable brand will be yanked from such competitors as Saks Fifth Avenue, Neiman Marcus and Nordstrom as those stores race to sign their own exclusive deals with designers.

Macy’s has a leg up on its smaller competitors in its ability to attract such exclusive deals, say industry experts.

“Every single one of these stores are doing their best to do deals with influencers and brands,” said Mortimer Singer, chief executive of retail advisory firm Traub.

Macy’s is also getting DKNY men’s outerwear and swim wear.

“It’s as meaningful a deal as they’ve done since Tommy,” Singer said.