Underwood shared her own sweet message to commemorate the day.
"Happy anniversary, babe! 11 years sure have flown by...here's to many, many more!" Underwood wrote. "Love you!"
This isn't the first time the couple has celebrated their anniversary on social media. Last year, the country superstar marked the occasion with a couple of adorable throwback photos of the couple in their youth.
"Hey you two crazy kids," Underwood wrote on social media last year. "Believe it or not, some day you both will become (slightly) less awkward, you'll grow up to have pretty cool jobs, you'll meet backstage at some girl's concert, fall in love, get married, have two amazing boys, and live happily ever after!"
Underwood even used the opportunity to poke fun at her husband's ultra-'90s bowl cut hairdo.
Underwood and Fisher, a former NHL player for the Nashville Predators, met in late 2008 backstage at one of her concerts. Fisher was a friend of Underwood's bass player Mark Childers, who'd been trying to set up the two for a while. They got engaged in 2009 and married in 2010 at the Ritz-Carlton resort on Lake Oconee, Georgia.
In 2015, the couple welcomed their first child, Isaiah Michael Fisher. In 2019, the couple welcomed second son, Jacob Bryan Fisher.
Underwood and Fisher frequently share their family outings on social media. Last year, the couple took up beekeeping and channeled their favorite Yellowstone characters for a horseback ride in Wyoming.