Lauren Sanchez is tacking "Bezos" onto her last name ... sharing a pic of herself in a gorgeous white wedding dress and changing her name on IG.

The star -- who held a wedding ceremony to Amazon founder Jeff Bezos on Friday in Venice, Italy -- shared the first look at the gown on her IG ... and changed her screenname to "Lauren Sanchez Bezos."

She also wiped her IG clean ... a fresh slate for the newlywed as she heads off into married life.

Vogue shared more pics of her wedding dress, which took 900 hours to make ... revealing it's a Dolce & Gabbana gown -- which we knew it would be after seeing pics of them outside a storefront for the big-time brand in Milan -- with a high-necked, hand-appliquéd Italian lace.

Lauren also told the outlet this is the first time she's ever worn a formal dress that covered her chest. She calls it a "departure from what people expect, from what I expect -- but it’s very much me.”

She stripped down in another shot from Vogue ... where she wore a tuxedo shirt like Jeff planned to for the ceremony -- teasing a hint of her cleavage in the sexy ensemble.

Sanchez also has more outfits coming this evening, BTW ... so stay tuned as more pics of these outfits come in.

The couple's wedding might be the big event ... but, there's still more on the way from their wedding week -- including parties all weekend before A-listers are expected to head home Sunday. Among those events is Friday's reception and a pajama party on Saturday.

A-listers have been flowing into the city all week ... from the Kardashian clan and Tom Brady to newly-single Orlando Bloom -- and ready to mingle Brooks Nader.

Like we told you ... bonds are being formed among the guys like Bloom, Brady and Leonardo DiCaprio at the party central of the event, The Gritti Palace. And, Sydney Sweeney is looking "f***ing beautiful" according to one source -- and capturing everyone's attention, including TB12.