"I'm so nervous, you guys", Cleopatra Bernard said as she took the stage to accept the award on her son's behalf.
Referring to the fact the awards were "voted for by the people", Swift said: "You know what else is voted on by the people?", before telling fans to "get out and vote" at the midterm elections.
For the month of October so far, 153,978 people have registered to vote. The midterm elections on 6 November.
While accepting her award for Artist of the Year, Swift called for her fans to head to the polls.
Swift - trading in her metallic red carpet dress for a sparkly black leotard - kicked off the awards show with an appropriately over-the-top rendition of her Reputation banger "I Did Something Bad". The rapper Cardi B won three awards, including one in tandem with Bruno Mars for their track Finesse. Thank you, guys, so much. In her photo caption, she admitted that she has been "reluctant to publicly voice my political opinions, but due to several events in my life and in the world in the past two years, I feel very differently about that now". She also condemned Republican senatorial candidate Marsha Blackburn for her voting record on women's rights and equal marriage.
The Walking Dead Season 9 Had the Lowest Rated Premiere Ever
AMC doesn't release numbers for the streaming service, though, so we don't know for sure how many people watched it there. From the Season 8 finale, the premiere was down approximately 23% in total viewers and 27% in the key demo.
She said she would support candidates in favor of LGBT equality and specifically cited the "systemic racism we still see in this country towards people of color is terrifying, sickening and prevalent".
Gladys Knight led a tribute to Aretha Franklin, who died of cancer in August at age 76.
Please, please educate yourself on the candidates running in your state and vote based on who most closely represents your values. At the Disco. The diva quota will be filled by headliners Jennifer Lopez, Carrie Underwood, Mariah Carey and the ever-provocative Cardi B.
XXXTentacion won for Best R&B Soul Album for 17 and his mother accepted the award in his honor.
Cabello's Havana took Pop/Rock Song and Underwood was recognised as the favourite Country Female Artist.