Swift - who revealed her political views for the first time in an Instagram post to fans earlier this week - was also called out by Billy Eichner earlier in the show, as he encouraged viewers to vote "like Taylor Swift told you to".
"I'm so nervous, you guys", Cleopatra Bernard said as she took the stage to accept the award on her son's behalf.
She also picked up three other awards, for best female pop artist, best tour, and best pop album for "reputation", the biggest seller of 2017.
He told the audience they should register to vote if they cared for "equality for women, for people of colour, for the LGBTQ community, if you believe that climate change is real".
Carrie Underwood was in ideal form vocally, and Camila Cabello - who won new artist of the year - gave a touching and vocally impressive performance of the ballad Consequences, earning her a standing ovation.
'Young people of America, the biggest election of our lifetime is happening on November 6.
Among the performances, a tribute to the late Aretha Franklin is planned.
Her logic is sound: If fans can learn to vote for their favorite music videos, why can't they apply that same skill to politics?
While accepting the award for artist of the year, Swift once again urged fans to vote during the upcoming midterm elections.
"Black-ish" star Tracee Ellis Ross will host the AMAs, which air live on ABC at 8 p.m. ET/ 5 p.m. PT.
Other winners on the night included Migos, Shawn Mendes, Camila Cabello and Carrie Underwood.
Elsewhere on Tuesday, New York rapper Cardi B, brought down the house with an exuberant performance of dance hit I Like It with J.Balvin and Bad Bunny.
DJ Khalid also gave a shout out Democratic Texas Senate candidate Beto O'Rourke when he won favorite male artist.
"Please, please educate yourself on the candidates running in your state and vote based on who most closely represents your values", she said.