"And Bo's sidekick Annie is home," Fisher announced on his Instagram Story Thursday.
Fisher, who recently became an American citizen, first welcomed Annie, after admitting owning a horse was a dream he held for most of his life.
"Ever since I was a kid I've always wanted horses," Fisher said. "Today I got my first! Bojangles is finally home! He'll have a dancing partner in a couple days."
Fisher's wife also shared the news of their latest family additions on her Instagram as well.
"Every cowboy needs a horse...and a hat," Underwood wrote in the post. "I'm still working with him on the Southern accent. Meet Bojangles...newest addition to the Fisher family!"
The family, which includes 4-year-old Isaiah and 2-month-old Jacob, also welcomed a new German Shepherd to their family, shortly before Jacob's birth.
"Meet the newest member of our family!" Fisher wrote on Instagram. "Isaiah affectionately named him Zero. I guess it fits because it's the chance of surviving if you try to break into our home."
The family, who recently relocated from their Nashville mansion to a custom-built estate located just outside of Music City, will soon take their family on the road, when Underwood kicks off her Cry Pretty Tour 360 in May, with her sons in tow.
"It's just all gonna happen at once," Underwood told PopCulture.com at a media event. "I went on tour with Isaiah when he was 11 months old. He was right there when we had our first show. And it was really hard. Obviously, I have help when I'm out there. Somebody's gotta watch my kid when I'm out on stage.
"But I'm really bad at utilizing that, which I think is good too," she added. "Nobody ever got up with my kid in the middle of the night. That was me, and I'm proud of that."
Underwood has been laying low since the birth of Jacob, but she will likely head to the 2019 ACM Awards, since she is nominated for Female Artist of the Year. The awards will occur just a few weeks before her Cry Pretty Tour kicks off on May 1, with Maddie & Tae and Runaway June serving as her opening acts.
Find dates at Underwood's website.
Photo Credit: Getty images/Rick Diamond