Swift won for Best U.S. Act and Best Video for "Me!", while Eilish scored the honors for Best Song for "bad guy" and Best New Artist.
Halsey took home the statuettes for Best Pop and Best Look, and BTS won for Best Live Act and Biggest Fans.
Green Day won for Best Rock, Martin Garrix for Best Electronic and FKA twigs Best Alternative.
The Best Collaboration title went to Rosalia and J Balvin for "Con Altura."
Singer, songwriter and YouTube star Becky G hosted the fan-voted prize presentation.