In a post to Instagram Wednesday night, Fisher snapped a picture of him and Underwood together on their couch, as they commemorated the milestone.
"9 years feels like 9 minutes!", Fisher captioned the photo. "Grateful to be on this journey with you @carrieunderwood!! Time sure does fly, adding the hashtags, "#datenight #happyanniversary."
The country music star and former NHL player tied the knot in July 2010 after first meeting at one of Underwood's concerts two years prior. They have since welcomed two sons, 4-year-old Isaiah, and 6-month-old Jacob, who was born earlier this year.
Underwood revealed the couple had went horseback riding earlier in the day, with a post on Instagram captioned, "Spent my morning with my cowboy and our horses!"
Underwood has frequently expressed her love for Fisher in public appearances, and even dedicated a recent CMT Music Award to him on his birthday.
In a June interview with People, the "Love Wins" singer confessed Fisher was the man she was "meant to be with," and that their relationship was "easy" compared to her past lovers.
“I feel like he is the person I was meant to be with,” the “Cry Pretty” singer told the magazine. “I had dated guys and kind of knew, like, ‘No.’ Nothing was ever really wrong, but nothing was really right either. With him, it was like a good partnership. It was an easy relationship to be in.”
Underwood also previously spoke about suffering three miscarriages before giving birth to her second child earlier this year, but said Fisher continued to stick by her side.
"He is so level headed about everything, and when I was dealing with everything, not just emotionally but hormonally, when you’re going on that roller coaster of pregnant, not pregnant, pregnant, not pregnant, I was probably not very easy to love, to be honest,” she said. “And to have somebody so even-keeled, he was my lifeline, keeping me grounded."