One Direction was named Artist of the Year and Best Duo or Group Pop/Rock, while The Weeknd took home the prizes for Best Soul/R&B Male and Best Album Soul/R&B for Beauty Behind the Madness.
Minaj scored the Best Rap/Hip-Hop Female title and her Pinkprint won for Best Album Rap/Hip-Hop.
Swift was deemed Best Artist Adult Contemporary, while her CD 1989 won for Best Album Pop/Rock and her hit "Blank Space" was voted Song of the Year.
Host Jennifer Lopez kicked off the show with an energetic dance tribute to some of the 2015's biggest hit songs. Leading a troupe of dancers wearing skin-tight, tribal-print bodysuits, Lopez danced to a medley that included "Thinking Out Loud," "Bitch Better Have My Money," "Hotline Bling," "Bad Love," "I Can't Feel My Face," "Uptown Funk" and "Anaconda."
Among the well-dressed celebrities seen on the red carpet before the event began at the Microsoft Theater were Zendaya, Gwen Stefani, Carrie Underwood, Kylie and Kendall Jenner, Hailee Steinfeld, Ciara, Julianne Hough and Selena Gomez, who later performed her song "Same Old Love."
Other performers included Justin Bieber, Coldplay, One Direction, Nick Jonas, Gwen Stefani and Ariana Grande, who won the prize for Best Pop/Rock Female. Additional highlights included a powerful duet by Alanis Morissette and Demi Lovato on Morissette's 1995 breakup anthem "You Oughta Know," as well as a capella group Pentatonix's performance of music from the Star Wars score with a full symphony orchestra and an introduction from actor Harrison Ford, and Celine Dion's rendition of Edith Piaf's "Hymne à L'Amour" in French as a tribute to those impacted by the recent terror attacks in Paris.
Sam Hunt was named Best New Artist, Ed Sheeran earned the accolade for Best Pop/Rock Male, Rihanna garnered the trophy for Best Soul/R&B Female and Fall Out Boy was declared Best Artist Alternative Rock.
The Collaboration of the Year award went to Skrillex & Diplo featuring Justin Bieber for "Where Are U Now."
The AMA for Best Country Male went to Luke Bryan, while Carrie Underwood won the same title in the female category. Pitch Perfect 2 won the honor for Best Soundtrack.
The prize presentation aired live on ABC.