'Little People, Big World' Stars Tori and Zach Roloff Celebrate Son Josiah's First Birthday

The 'Little People, Big World' stars are also parents to Jackson and Lilah.

Tori and Zach Roloff celebrated a special milestone!

On Sunday, the Little People, Big World stars' youngest son, Josiah, turned one. Proud mom Tori marked the occasion with a sweet post.

"Happy birthday Josiah!" Tori wrote next to a video set to Brent Morgan's song, "Forever and Ever, Amen."

In the video, the birthday boy sits in a highchair (posted in front of a banner that reads: Josiah's First Rodeo) surrounded by rodeo-themed balloons as he eats his birthday cake. The video then cuts to a moment with Tori was holding him in the hospital, shortly after his birth. 

Earlier in the day, Tori penned a sweet message dedicated to her baby boy.

"Happy birthday to our sweet Josiah! 🎉🎂🎈," she wrote. "We love you so much Si! You are the sweet guy ever. You are always so happy and love watching your family. You are on the move and ready for any adventure! You love eating and bath time and I love how obsessed you are with your siblings!! I have loved getting to love on you the last year si si! Let’s celebrate all day long!!"

Next to the post was a set of pictures that saw Josiah wearing overalls and a big black cowboy hat as he posed for the camera.

Prior to his birthday photo shoot, Tori gave one final months-old update and shared Josiah's latest milestones with her followers. 

"12 months of Josiah!," she wrote next to the picture of her and Zach's baby boy laying on the same mat she has used since his first month milestone.

"I’ve said it from the moment I met you, it’s like you were always here!! This last year I have loved getting to know you and watching you grow!! Happy birthday sweet boy! Josiah is pulling himself up and ready to walk! 👣 Si is always so smiley and content 😃 He loves eating and bath time! 🛁 Josiah is clapping and waving! 👋🏼 He is currently not loving bed time and has complete fomo when it comes to hanging with his fam! 🛏️ We love you Josiah! The last 12 months have seriously been a gift! I can’t wait to celebrate you all day today! Ps. So glad these photos are done- they were getting impossible! This kid never sits still!!."

Tori, 31, and Zach, 32, are also parents to Jackson, 5, and Lilah, 3. 

In October, Zach and Tori -- and a then 6-month-old Josiah -- sat down for an interview with ET, where they opened up about life at home with their latest addition.

"He started liking solid food," Tori told ET's Cassie DiLaura. "He sleeps when he wants to ... occasionally."