Kate Chastain’s son Sullivan turns 1: See how the Below Deck alum celebrated his birthday

Below Deck alum Kate Chastain marked a significant milestone with her son Sullivan on Friday.

The little guy celebrated his first birthday, and Kate happily let her fans in on the festivities.

On Instagram, Kate shared a carousel of photos from Sullivan’s big day.

Sullivan was all smiles in the first couple of pictures, as Kate held a flower up for him to smell.

In the last pic, Sullivan was too cute for words with his messy hair, clothes, and look on his adorable face.

“Baby 1 year old birthday tuxedo for sale. Slightly used.” read the caption on Kate’s IG post.

The proud mama shared the same images on X (formerly Twitter) but used a different caption.

“1 year old going on 26 🎉,” she wrote.

Kate Chastain reflects on her first year of motherhood

In another Instagram post, Kate shared a video of various moments from Sullivan’s first year. Set to Let’s Hear It for the Boy by Deniece Williams, Kate reflected on her first year of motherhood.

The video even included footage from Sullivan’s birthday with the signature first birthday cake.

“My debut album titled ‘First year as a mom’ includes the hit songs:

‘what’s the matter with the baby’

‘shut your eyes and shut your mouth’ and

‘I thought I’d be a cool mom…’ Kate captioned the IG post.

It didn’t take long for the comments sections of both of Kate’s Instagram posts to become flooded with familiar Below Deck faces.

Below Deck stars gush over Kate Chastain and her son Sullivan

Hannah Ferrier from Below Deck Med let Kate know how adorable Sullivan is and wished him a Happy Birthday. Below Deck Sailing Yacht alum Dani Soares wrote, “Happy birthday Sullivan and happy birthday Kate, that first year is a wild ride 🙌👏👏.”

Kate’s Below Deck Season 7 costar and good friend Courtney Skippon also popped in the comment section to say it felt longer than a year. Courtney also gushed over watching Kate as a mom.

Courtney and Kate’s Season 7 colleague Tanner Sterback called Sullivan a “legend” while wishing him a Happy Birthday.

Josiah Carter, also a good friend of Kate’s, called Sullivan his spirit animal, while Below Deck Sailing Yacht chief stew Daisy Kelliher called Sullivan adorable.

“Just the sweetest little munchkin 🫶🏽,” Below Deck’s Fraser Olender expressed.

Kate Chastain had much to celebrate this week as her son Sullivan turned one year old. The Traitors alum used her sassy wit and charm to honor Sullivan’s milestone.

Below Deck airs Mondays at 9/8c on Bravo. Seasons 1-11 are streaming on Peacock.