Maroon 5, still riding high off their comeback hit "Moves Like Jagger," won for favorite pop-rock band/duo/group. Adam Levine, the band's lead singer and "The Voice" judge, thanked "our incredible fans for making this happen."
Swift won country female artist.
The ceremony inside the Nokia Theatre in an unusually rainy Los Angeles was dripping with musical performances from such acts as The Band Perry, who crooned an emotional "If I Die Young," and a platinum-blonde Chris Brown, who sang a stripped-down "All Back" before being joined by helmet-clad back-up dancers for a high-energy routine to "Say It With Me."
Nicki Minaj launched the 39th annual fan-favorite ceremony with a performance featuring tethered back-up dancers, stilt-walking robots and super-producer David Guetta emerging from behind a pillar of speakers. The pink-haired singer - wearing a pair of speakers on her much-talked about posterior - kicked off the show with "Turn Me On" before launching into "Super Bass."
Minaj later won favorite rap/hip-hop artist, besting a group that included her mentor, Lil Wayne.
"There's so much love in this room," said Minaj, who also thanked Swift, a big fan of her "Super Bass" hit.
Justin Bieber got in the holiday spirit with "Under the Mistletoe," before Kelly Clarkson, wearing a glittery red gown with her hair swept to the side, delivered a swinging rendition of her "Mr. Know It All" as back-up dancers dressed as 1930s-era photographers snapped the first-ever "American Idol" champion.
Adele leads the nominees with four nods at this year's AMAs, which honor music artists based on online votes.