Victoria’s Secret has tapped its first size-14 model — but the lingerie giant didn’t announce the news, and its customers learned about it on the model’s Instagram feed.

The struggling bra-and-panties peddler, which for decades has used only skinny models in its fashion shows and marketing campaigns, signed plus-size model Ali Tate Cutler as part of its new partnership with London-based lingerie brand Bluebella.

Victoria’s Secret announced the Bluebella tie-up last week, noting in a press release that the UK label — which includes plus-size models in its ads alongside skinny ones — is about “self-love, self-acceptance and championing individuality.”

Nevertheless, it was Cutler herself who revealed that Victoria’s Secret may have crossed a historic threshold of sorts.

“I believe I’m the first size 14 on @victoriassecret?” Cutler wrote on her Instagram account last week. “Great step in the right direction for bodies.”

The UK company’s provocative duds — which feature garter belts and skimpy body suits with straps, thongs and pricey bras for $62 — began selling in Victoria’s Secret stores in the US on Friday and will be in its UK stores this coming Friday.

Victoria’s Secret, owned by Columbus, Ohio-based L Brands, has been blasted for excluding larger women from its sex-driven ads.

This summer, the chain began to relent by signing its first transgender model, Valentina Sampaio, and then a handful of curvier models. The changes followed the departure of longtime chief marketing officer Ed Razek, who once said that Victoria’s Secret wouldn’t use transgender or plus-size models because it is “selling a fantasy.”

Cutler is one of four models featured in the launch of Bluebella, and is the only plus-size model among them. Nevertheless, Bluebella’s racy designs signal that Victoria’s Secret is doubling down on sexy, said retail consultant Gabriella Santaniello of A-Line Partners.

“They seem to be saying we are going to stay unapologetically sexy and moving in the opposite direction of comfortable, functional lingerie,” Santaniello said.