Lauren Sanchez doesn't need to wait until Wednesday to wear pink ... pulling off a Barbie-chic dress while enjoying an island vacay to kick off her new year.

The former entertainment reporter was walking around Gustavia, St. Barts, earlier this week in the form-fitting dress ... cut out at the sides, revealing her tan skin underneath.

The dress ends pretty high on her legs ... more of a summer number than one worn in the dead of winter -- though St. Barts has gorgeous weather year-round, to be fair.

No Jeff Bezos during Lauren's shopping trip ... but, she was joined by pal October Gonzalez, the wife of Tony Gonzalez ... the former NFL star -- and Lauren's ex-husband.

The pair of pals hit up a few luxury stores down in the country ... including Prada, Dolce & Gabbana and Louis Vuitton as they strolled along the port.

As you may remember ... Sanchez and Gonzalez have nailed co-parenting their son  -- celebrating their son Nikko's college graduation with their respective significant others over summer.

Now, they're enjoying full-on vacations together ... hanging out on the yacht as a group earlier this week.