The 29-year-old Ottawa Senators star reportedly proposed to the 26-year-old Underwood on Sunday afternoon at his home, and she accepted.
"We're both obviously excited and very happy," Fisher told the Toronto Sun on Monday.
Underwood and Fisher have been dating for roughly a year and Underwood said that's "the longest relationship" she's ever had during a November appearance on The Ellen DeGeneres Show.
In addition, Underwood said during the appearance that she and Fisher had no plans to move in with each other until they were wed.
"Call me old-fashioned. He's there. I'm here," said Underwood at the time. "We're both doing our thing and it's good. The next guy I move in with will be my hubby -- whoever that is. I'm not saying it's going to be him."
Underwood -- who has previously dated Gossip Girls star Chace Crawford and Dallas Cowboys quarterback Tony Romo -- received two Grammy nominations earlier this month.
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