The Love Song hitmaker faced tough competition from her pop peers Pink, Rihanna, Katy Perry and Nicki Minaj, but managed to beat out the competition to claim Sunday night's (11Nov12) first prize.
After being presented with the award from Lana Del Rey, a jubilant Swift told the crowd, "This is my first ever Ema, I'm so excited. Thank you so much to the fans who voted, this is unreal."
It was a promising start to what is sure to be a big night for Swift - she's up for five nominations at the prizegiving.
Rita Ora kicked off the show by opening the event with her hit R.I.P., while fun. and Carly Rae Jepsen also thrilled the audience with performances of their respective chart smashes We Are Young and Call Me Maybe.
German supermodel Heidi Klum is hosting the ceremony.