In the song, Underwood takes a baseball bat to a cheating boyfriend's "pretty little souped up 4-wheel drive."
"It was at the CMT awards last year that I gave my first acceptance speech ever," Underwood said. "It's been such an amazing and blessed two years."
Kenny Chesney won male video for "You Save Me" and Rascal Flatts won group video for "What Hurts the Most."
Jack Ingram received the Wide Open Country award, a new category intended to honor artists outside the mainstream.
Viewers chose Ingram's video over Johnny Cash's "God's Gonna Cut You Down," rockers Sheryl Crow and Sting for their duet "Always on Your Side" and Jimmy Buffett's "Bama Breeze."
Photos: CMT Awards 2007
"Right now I'm flying on the mainstream radar, but for a long time I wasn't," Ingram said.
Teen newcomer Taylor Swift captured breakthrough video of the year honors with her hit "Tim McGraw."
Later, the 11th grader said she was taking her final exams Tuesday. She attended the show with her mother.
"This is my first award show ever. I wanted my mom right next to me," Swift said.
Sugarland won duo video of the year for "Want To."
"Thank you to the fans," singer Jennifer Nettles said. "We love that you vote for that; it makes it that much more special."
Kris Kristofferson, who penned country classics like "Sunday Morning Coming Down" and "Help Me Make it Through the Night," received the Johnny Cash Visionary Award.
Kristofferson, 70, joins previous winners Hank Williams Jr., Loretta Lynn, Reba McEntire, the Dixie Chicks and his late friend Johnny Cash.
Cash's daughter, Rosanne Cash, presented the award, and Kristofferson received a standing ovation at the Curb Event Center at Belmont University.
"He is an artist with nothing to lose," Rosanne Cash said. "He can risk everything because he never compromises his integrity."
Kristofferson praised the late Johnny Cash and said, "Bob Dylan said it best. He said John was like the North Star: you could guide your ship by him." Then Kristofferson looked up and raised the award high above his head in tribute to his late friend.
Later, Kristofferson recalled time spent at Cash's lakeside home near Nashville that was destroyed by fire last week.
"We used to go down there when we got down on our spirits," he said. "My wife put it best, though, when she said John and June (wife June Carter Cash) took everything that really mattered with them."
Comedian Jeff Foxworthy hosted the show, and performers included Rascal Flatts, Chesney, Toby Keith, Sugarland and Bon Jovi.
Foxworthy recapped the year in country music, including Dolly Parton's Kennedy Center Honor.
"That's appropriate because if there's ever been a president who would enjoy Dolly Parton it's President Kennedy," he quipped.
But he quickly became serious when he addressed the fatal shootings at Virginia Tech.
"There are a lot of hurting people associated with Virginia Tech and we want those people to know in the days and weeks going forward that you are going to be in the hearts and minds of everyone in the country music community," Foxworthy said. "God bless you."
The Dixie Chicks were nominated for video of the year and group of the year their first such nominations since country radio unofficially banned them.
But the Chicks were nixed in both categories.
The trio has been at odds with country radio since lead singer Natalie Maines told a London audience in 2003 that they were ashamed President Bush was from their home state of Texas.
But even without radio airplay, they managed to win three Grammys and sell 2 million copies of their latest album, "Taking the Long Way."
"I understand the songs on that album are great, but I listen to country radio so I haven't heard them yet," Foxworthy cracked.