The 21-year-old social media influencer was just announced as one of the models receiving the distinction for the 60th anniversary of the swimsuit issue ... putting her in the company of big names like Olivia Culpo, Brooks Nader, Emily Ratajkowski and Kate Upton, who are all former rookies for the publication.

Dunne flew to Portugal as part of the gig ... rocking a white Ola Vida suit and BABEN skirt for her photoshoot.

Of course, Livvy famously posed for the S.I. swimsuit issue in 2023 ... with editor M.J. Day explaining it was to show the student-athlete is much more than a pretty face.

Following the massive popularity of Livvy's first appearance, the mag said it was a no-brainer to bring her back.

"The decision to invite Livvy back to appear in the 2024 issue as a rookie was an easy one," Day said. "Last year, we featured Livvy the D1 athlete, highlighting her accolades as an all-academic and an all star on the rise. This year, we are featuring Livvy as a well-established, industrious entrepreneur who is here to stay, who continues to break barriers, continues to work hard and forge an unforgettable path for herself and future generations of female athletes."

"Like all the incredible women that represent SI Swimsuit, Livvy stands out in her own unique and critical way. We are so incredibly proud of what she continues to achieve and are so excited to welcome her back not as Livvy Dunne the LSU D1 gymnast, but Livvy Dunne, the Sports Illustrated Swimsuit rookie."

Livvy also spoke about getting the nod ... adding, "Coming back for Year 2, I mean, last year I said it was a dream come true, and nothing’s changed. It's still a dream come true. I can't believe I can call myself a rookie. It feels unreal."

Dunne said posing for S.I. has helped her feel comfortable in her own skin ... and she hopes young girls everywhere will see her and get the same message.