Rihanna has nominations in six categories, including Best Female, Best Song and Best Video.
Swift is close behind with five nominations, including Best Live Act and Best Look.
The two are going up against each other in the prestigious Best Pop Act category, alongside Justin Bieber, No Doubt and Katy Perry, and they will also battle it out for the title of Best Female, with the shortlist also featuring Perry, Pink and Nicki Minaj.
In the Best Male category, Bieber has another nomination but faces some tough competition from hip-hop heavyweights Jay-Z, Kanye West, Flo Rida and Pitbull.
Bieber and Perry have notched up four nominations each, and Lady Gaga, Nicky Minaj, and Lana Del Rey are among the acts receiving three. The winners will be announced at a ceremony in Frankfurt, Germany, on Nov. 11.
The full list of main nominations is as follows:
Best Pop Act: Justin Bieber, No Doubt, Katy Perry, Taylor Swift, Rihanna
Best Song: Carly Rae Jepsen, "Call Me Maybe"; Rihanna feat. Calvin Harris, "We Found Love"; Gotye, "Somebody That I Used to Know"; Pitbull feat. Chris Brown, "International Love"; fun. feat. Janelle Monae, "We Are Young"
Best Female: Rihanna, Katy Perry, Pink, Taylor Swift, Nicki Minaj
Best Male: Justin Bieber, Kanye West, Flo Rida, Pitbull, Jay-Z
Best New Act: Rita Ora, fun., One Direction, Lana Del Rey, Carly Rae Jepsen
Best Live Act: Taylor Swift, Lady Gaga, Jay-Z and Kanye West, Green Day, Muse
Best Hip Hop: Jay-Z and Kanye West, Nas, Rick Ross, Drake, Nicki Minaj
Best Rock: Linkin Park, Green Day, Muse, the Killers, Coldplay
Best Electronic: David Guetta, Swedish House Mafia, Avicii, Skrillex, Calvin Harris
Best Alternative: Jack White, the Black Keys, Arctic Monkeys, Florence + the Machine, Lana Del Rey
Best Video: M.I.A., "Bad Girls"; Lady Gaga, "Marry the Night"; Katy Perry, "Wide Awake"; Rihanna feat. Calvin Harris, "We Found Love"; PSY, "Gangnam Style"
Best Look: Nicki Minaj, Rihanna, Jack White, Taylor Swift, A$AP Rocky
Best World Stage: Arcade Fire, Arctic Monkeys, B.o.B, Evanescence, Flo Rida, Jason Derulo, Joe Jonas, Justin Bieber, Kasabian, Ke$ha, LMFAO, Maroon 5, Nelly Furtado, Red Hot Chili Peppers, Sean Paul, Snoop Dogg, Snow Patrol, Taylor Swift
Biggest Fans: Justin Bieber, One Direction, Lady Gaga, Rihanna, Katy Perry
Best Push: Foster the People, Lana Del Rey, Mac Miller, Michael Kiwanuka, Gotye, Rebecca Ferguson, fun., Rita Ora, Conor Maynard, Of Monsters and Men, Carly Rae Jepsen
I'm sorry, but they both stink as far as I'm concerned. Riri keeps pining away for someone that once beat the crap out of her AND bit her. WOW, brilliant role model for up and coming young girls, not to mention, obvious self-esteem issues. Taylor's music on the other hand is just boring, all her songs sound the same, and I'm super tired of her making a poor me song over every d-bag she's dated. I think we've all dated some jerks in our time, suck it up and move on. And really, what do you expect when you date someone like J Mayer, who's already been in the media for for his actions towards women, does she not know how to read??!
I say give it to anyone BUT these two!