She's only 21, but this is already her second time winning the CMA's top prize.
"I am freaking out," she said. "It's one thing to win it once and you're like, 'Yeah, that was the craziest, biggest deal of my life.' And then to win it again, this can't be possible."
Miranda Lambert won the female vocalist honor, joking on stage about her husband, Blake Shelton, who took home the male vocalist honor.
"Miranda came and sat down after she won hers and she goes, 'Did we pay somebody? How in the hell did this happen?'" Shelton said.
Sugarland won the vocal duo award, with Lady Antebellum taking the vocal group honor.
Jason Aldean's "My Kind of Party" won album of the year.
The Band Perry went on a roll, winning the new artist prize, plus single of the year for "If I Die," with Kimberly Perry winning the song of the honor for writing it.
Awards aside, the night's more emotional moment came with a superstar salute to country icon Glen Campbell, performed by Keith Urban, Brad Paisley and Vince Gill.
Campbell, who is bravely battling Alzheimer's disease, said he was touched.
For a full list of winners, visit OnTheRedCarpet.com.