The "Anti-Hero" singer thanked voters for supporting her after releasing four original albums and two re-recordings in the last three years.
"The more music I made and the more music I put out, the happier I was, the more I just kept that channel open and just kept creating, kept making things. And the more that happened, the more you guys were like, yeah, I keep doing it. And the happier I was. So, I have the fans to thank, essentially for my happiness, and I love you more than I can say," she said on stage at the awards show in Los Angeles.
Earlier, Swift's re-recording of her 2012 record "Red" took the trophy for a favorite pop album. The 32-year-old singer has been making new versions of albums from her past after a dispute with her former record label.
Swift did not mention last week's controversy over Ticketmaster's sales for her upcoming tour, which were filled with glitches and prompted the company to apologize to her.
In the artist of the year category, Swift triumphed over formidable names including Beyonce, Harry Styles, The Weeknd, Drake, Adele and Bad Bunny.
Singer Pink opened the awards show dancing and singing on roller skates to her upbeat song "Never Gonna Not Dance Again."
Dove Cameron, a former Disney Channel actress who reached the Billboard charts this year with the pop single "Boyfriend," earned the first trophy of the night with her best new artist win.
Collecting her award, she thanked the LGBTQ community and spoke of the importance of visibility, after a gunman opened fire inside an LGBTQ nightspot in Colorado Springs late on Saturday (November 19), killing at least five people and injuring 25 others
"On the heels of the tragedy that happened at Club Q in Colorado Springs, I want to remind everyone how important queer visibility is and how important our community is," she said.
Machine Gun Kelly, wearing a purple suit with long silver spikes, was named favorite rock artist.