Inside Paris Hilton’s extravagant sea-themed first birthday for son Phoenix: From transforming her backyard with fish-shaped balloons and seaweed to numerous celebrity attendees – from Lance Bass to Kelly Osbourne

Paris Hilton pulled out all the stops to make sure her son Phoenix’s first birthday was absolutely perfect.

To celebrate her baby boy’s milestone, the reality star, 42, threw a ‘Living Under the Sea’ themed bash at her home on Saturday, attended by Lance Bass, Kelly Osbourne and Rumer Willis.

The mother-of-two transformed her backyard to look like the bottom of the ocean with a whimsical arch filled with red, blue and orange balloons as well as a few in the shapes of various fish.

Hilton even played music from Disney’s The Little Mermaid over the speakers and decorated her patio with seaweed.

Paris Hilton pulled out all the stops to make sure her son Phoenix's first birthday was absolutely perfect

Paris Hilton pulled out all the stops to make sure her son Phoenix’s first birthday was absolutely perfect

To celebrate her baby boy's milestone, the reality star, 42, threw a 'Living Under the Sea' themed bash at her home on Saturday, attended by Lance Bass, Kelly Osbourne and Rumer Willis.

To celebrate her baby boy’s milestone, the reality star, 42, threw a ‘Living Under the Sea’ themed bash at her home on Saturday, attended by Lance Bass, Kelly Osbourne and Rumer Willis.

The businesswoman, who is married to Carter Reum, even got a 'unicorn' to entertain the little ones and partygoers

The businesswoman, who is married to Carter Reum, even got a ‘unicorn’ to entertain the little ones and partygoers

‘It’s Phoenix’s first birthday and we have a ‘Living Under the Sea’ theme. I’m so excited,” she excitedly told her followers.

She continued: ‘I’ve thrown amazing birthday parties all my life. So to be able to do this now for my little boy is such a special memory.’

For the occasion, the social media mogul wore a long blue dress, white sunglasses, princess crown and a large quilted Chanel bag.

The birthday boy wore a white t-shirt, khaki pants and a stylish newsboy cap.

In a video, which was uploaded to her Instagram story, Hilton can be seen holding Phoenix as he brings him a petting zoo, complete with bunnies, baby goats, chickens and sheep, to the party.

The businesswoman, who is married to Carter Reum, even brought a ‘unicorn’ to entertain the little ones and partygoers.

Hilton’s youngest, London Marilyn, two months, was also present.

On Friday’s episode of The Jennifer Hudson Show, Hilton teased that she has “big plans” to ring in her first child’s birthday with a petting zoo, “ball pit and slides.”

The mum-of-two transformed her backyard to look like the bottom of the sea with a whimsical arch filled with red, blue and orange balloons as well as a few in the shapes of various fish

The mum-of-two transformed her backyard to look like the bottom of the sea with a whimsical arch filled with red, blue and orange balloons as well as a few in the shapes of various fish

To celebrate her baby boy's milestone, the reality star, 42, threw a 'Living Under the Sea' themed bash at her home on Saturday, attended by Lance Bass, Kelly Osbourne and Rumer Willis.

To celebrate her baby boy’s milestone, the reality star, 42, threw a ‘Living Under the Sea’ themed bash at her home on Saturday, attended by Lance Bass, Kelly Osbourne and Rumer Willis.

Hilton even played music from Disney's The Little Mermaid over the speakers and decorated her patio with seaweed

Hilton even played music from Disney’s The Little Mermaid over the speakers and decorated her patio with seaweed

'It's Phoenix's first birthday and we have a ¿Sliving Under the Sea¿ theme.  I'm so excited,' she excitedly told her followers

‘It’s Phoenix’s first birthday and we have a ‘Living Under the Sea’ theme. I’m so excited,” she excitedly told her followers

She continued: 'I've thrown amazing birthday parties all my life.  So to be able to do this now for my boy is such a special memory'

She continued: ‘I’ve thrown amazing birthday parties all my life. So to be able to do this now for my boy is such a special memory’

For the event, the social media mogul wore a long blue dress, white sunglasses, princess crown and a large quilted Chanel bag

For the event, the social media mogul wore a long blue dress, white sunglasses, princess crown and a large quilted Chanel bag

“I know he’s only one, but all the parents are coming and there will be some older kids too,” she explained. ‘It will be fun for all ages at home. It’s going to be very sweet.’

Earlier this month, Hilton tagged her baby boy on Instagram by sharing sweet snaps of his first year.

“One year ago, a beautiful angel baby entered our lives, bringing so much love and happiness,” she began.

“My precious little one, you are more than a dream come true,” the reality TV personality continued. “You make my life complete.”

The birthday boy wore a white t-shirt, khaki pants and a stylish newsboy cap

The birthday boy wore a white t-shirt, khaki pants and a stylish newsboy cap

In a video, uploaded to her Instagram story, Hilton can be seen holding Phoenix as he brings him a petting zoo, complete with bunnies, baby goats, chickens and sheep, to the party

In a video, uploaded to her Instagram story, Hilton can be seen holding Phoenix as he brings him a petting zoo, complete with bunnies, baby goats, chickens and sheep, to the party

On Friday's episode of The Jennifer Hudson Show, Hilton teased that she has

On Friday’s episode of The Jennifer Hudson Show, Hilton teased that she has “big plans” to ring in her first child’s birthday with a petting zoo, “ball pit and slides.”

Hilton seen sliding into a ball pit

Hilton seen sliding into a ball pit

On motherhood, she added: ‘Every day with you is a precious gift, and I am endlessly grateful to be your mum.

“Celebrating your first of many birthdays, Baby P,” she wrote. ‘Here’s to a lifetime of laughter, love and wonderful adventures with our adorable crew! Happy 1st Birthday!’

The cover photo of her stunning photo album showed Hilton in a pink fur coat cradling a then-baby Phoenix on their private jet.

The mother-son duo seemed to share a moment as they both gazed adoringly into each other’s eyes.

She then shared a photo of Phoenix bundled up in a onesie and knit hat as he sat beaming on the couch in front of a portrait of her on the wall.

She got a sweet kiss on the cheek from her friend Lance Bass at the celebration

She got a sweet kiss on the cheek from her friend Lance Bass at the celebration

Phoenix smiled as he petted a baby goat with its mother

Phoenix smiled as he petted a baby goat with its mother

Paris gave a special shout out to Balloon and Paper for transforming her backyard for the bash

Paris gave a special shout out to Balloon and Paper for transforming her backyard for the bash

The Simple Life star also posted a photo of herself looking tenderly at her baby son as he cradled him with his back against her chest.

Two more snaps in the series showed Phoenix, dressed in a onesie doctor costume, sitting on a plush chair in his nursery.

Surrounded by stuffed animals and toys in the photos, he posed and smiled sweetly for the camera.

The entrepreneur also shared a photo of Phoenix riding a toy unicorn while Hilton sat next to him on the ground, gazing lovingly at him.

Earlier this month, Hilton marked her baby boy turning one on Instagram by sharing sweet snaps of his first year

Earlier this month, Hilton marked her baby boy turning one on Instagram by sharing sweet snaps of his first year

She and Reum, who welcomed their second child via surrogate in November, married in 2020 at a private estate in Los Angeles.

She and Reum, who welcomed their second child via surrogate in November, married in 2020 at a private estate in Los Angeles.

Another photo showed Phoenix sitting in a car seat while wearing sunglasses and a baseball cap.

Hilton shared a photo of him with her in the recording studio as seen in her latest TikTok post – in which she announced that she was working on her second album.

She also posted him in another costume onesie with a cowboy hat on his head.

The final addition to her post was a clip of Phoenix cooing as Hilton raved about her ‘cute’ and ‘handsome’ son.

In the carousel post, she only shared photos of Phoenix and herself, but none of her husband or their second child.

Hilton and the venture capitalist – whom she married at a private estate in Los Angeles in 2021 – also welcomed daughter London Marilyn via surrogate in November 2023.