Hilton’s little boy was showered in love as he celebrated his “Sliving Under the Sea” themed event.

Paris Hilton and son Phoenix with Rick and Kathy Hilton (L), Paris Hilton and son Phoenix with Kelly Osbourne and son Sidney (R). PHOTO: 

Paris Hilton’s little boy was surrounded by a lot of love at his first birthday party.

On Sunday, the multi-hyphenate mom, 42, celebrated son Phoenix Barron’s first birthday in a “Sliving Under the Sea”-themed bash with family and friends.

The birthday boy had a lot of special guests to enjoy the attractions — which included sand art, a petting zoo, and beautiful aquatic-themed balloon displays — posing with them in a series of photos.

Hilton and Phoenix could be seen with Kelly Osbourne and toddler son Sidney, 14 months, in one photo. In others, the duo poses with Lance Bass and his twins Alexander and Violet, 2, model Jessica Hart. Selma Blair, Rumer Willis and daughter Louetta Isley, 9 months, and more.

Paris Hilton with Michael Turchin and Lance Bass and their twins, Violet and Alexander.KEVIN OSTAJEWSKI

There was no shortage of family on hand to celebrate Phoenix as well. Dad Carter Reum appeared in a number of photos, though little sister London, 11 weeks, wasn’t pictured amid the action. The toddler posed with Hilton and his grandparents, Rick and Kathy Hilton, in one beautiful photo.

Another shot shows mother and son posing with Hilton’s brother, Barron Hilton, his wife Tessa — who is currently expecting the couple’s third baby — and their two kids, Caspian Barron, 16 months, and daughter Milou Alizée, 3½.

Barron Hilton and son Caspian, Paris Hilton, Tessa Hilton and daughter Milou.KEVIN OSTAJEWSKI

In an intimate chat with Reum on the “Stars Are Blind” singer’s I Am Paris podcast in April, Paris shared how excited she is to see her little ones bond with their cousins as they grow.

“It’s so cute to have all the next generation of cousins growing up together,” she said.

In addition to Paris and Barron’s kids, sister Nicky Hilton Rothschild is also a mom, sharing an 18-month-old son and daughters Theodora “Teddy” Marilyn, 5, and Lily-Grace Victoria, 6, with husband James Rothschild.

“Barron just had his baby. My sister Nicky just had her baby boy, and then your sister just had her baby girl,” she said to Reum. “So they’re literally all only a few months apart,” also noting cousin Brooke Wiederhorn — daughter of Kim Richards — welcomed a baby girl in December.

Naming a few other babies in his family, the entrepreneur noted, “They’re gonna have a cool cousin friend group.”