Just moments before the announcement, the 36-year-old — dressed in a floral top paired with a neon pink skirt — was performing her latest single, "Southbound."
Underwood, 36, beat out the other Video of the Year nominees including, Kelsea Ballerini's "Miss Me More," Kane Brown's "Good as You," Luke Combs' "She Got the Best of Me" and "Coming Home" by Keith Urban and Julia Michaels.
Along with Video of the Year, Underwood also won the night's first televised accolade — Female Video of the Year — for her song "Love Wins" at the Bridgestone Arena in Nashville, Tenn. Underwood's wins Wednesday night extends her run as the most decorated act in the history of the CMT Music Awards.
"It is my husband's birthday today — look what they got you," said Underwood as she accepted the female video of the year award while the camera panned to her hubby, former hockey player Mike Fisher.
To kick off one of country music's biggest nights, Thomas Rhett and Little Big Town members Karen Fairchild, Jimi Westbrook, Kimberly Schlapman and Philip Sweet — joined by Trombone Shorty — did a lively performance of Rhett's "Don't Threaten Me With A Good Time."
Kane Brown was up next, treating viewers to a performance of his tune "Short Skirt Weather." Following the 25-year-old's act, Little Big Town — who hosted the show for the second year in a row — returned to the stage to deliver their opening monologue, which consisted of poking fun at a recent "Game of Thrones" blunder.
"It's the breakout star of 'Game of Thrones' — a Starbucks cup," the band said, teasing the coffee cup which was accidentally featured in a recent "GoT" episode.
The band also sang some of "Old Town Road," the No. 1 country-rap hit from newcomer Lil Nas X, that was booted from the Billboard country charts when the song was deemed not country enough.
Later in the show, Little Big Town also performed "The Daughters," while Luke Bryan sang his latest single "Knockin' Boots." Kelsea Ballerini rocked the stage with her tune "I Miss Me More" and Brett Young teamed up with Boyz 2 Men for an amazing collaboration of "Here Tonight."
More collaborative performances followed including Sheryl Crow and Maren Morris, while Tanya Tucker — whose new album will be produced by Brandi Carlile — sang "Delta Dawn" with the Grammy-winning singer, Martina McBride, Trisha Yearwood, Lauren Alaina and more acts.
While accepting the award for Group Video of the Year, Zac Brown — of the country band with the same name — delivered a strong message for his haters when his group won.
"We're so grateful and we get our award every night when we [perform for our fans]," Brown — representing the rest of his bandmates after the video for their hit song "Someone I Used to Know" won — said. "This award is for all of you, my band and all the outsiders that waited through everyone's doubts.
"For you young artists, have courage to stand up against the machine," he added before telling his "haters" to "f--- off."
When Ashley McBryde won breakthrough video of the year, she took a drink from Luke Combs — who won CMT performance of the year for "Beautiful Crazy" from the series "CMT Crossroads" — as she walked to the stage.
"I'm always awkward and I usually bring my drink with me, but I didn't have a drink so I took Luke Combs' drink," said McBryde, who scored Grammy and Emmy nominations this year.
Keith Urban and Julia Michaels — the pop singer who has co-written hits for Justin Bieber, Selena Gomez and herself — won collaborative video of the year for "Coming Home," while Kane Brown won male video of the year for "Lose It."
Fox News' Sasha Savitsky and The Associated Press contributed to this report.