The 34-year-old singer and former "American Idol" winner penned a sweet note to Fisher on Thursday after the Nashville Predators captain retired after 17 years with the NHL.
"Captain @mfisher1212 I sure am going to miss watching you play and cheering you on with the rest of Smashville, but I so look forward to seeing what God has in store for you in this next chapter of your life," Underwood wrote.
"You've given your teammates and the game your all for so many years... you've worked so hard and made us all so proud!"
"Isaiah and I love you so much and are so excited to be able to have you home a lot more..." she said of their 2-year-old son. "We can't wait to cheer on the @predsnhl WITH you in the stands! #ThankYouSmashville #PredsFansForLife."
Fisher announced his retirement in a letter published in The Tennessean on Thursday.
The 37-year-old hockey player played for the Ottawa Senators and the Nashville Predators during his NHL career.
"This is the hardest decision I've ever had to make, but I know I've made the right one," Fisher wrote.
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"This job I've been able to have for a majority of my life is so much fun," he said.
"To help create that entertainment and to see the joy we can bring to people is such a unique and exciting opportunity. I'll miss my teammates, my coaches and the game itself."
Underwood and Fisher celebrated their seventh wedding anniversary in July.
The singer shared her gratitude in an Instagram post at the time, saying she feels "so blessed to share this life" with Fisher.
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