Coldplay kicked off the ceremony with a rousing rendition of their hit Every Teardrop Is A Waterfall.
Frontman Chris Martin shouted to the crowd at Belfast’s Odyssey Arena: “Shout for Justin Bieber!”
Katy Perry won the first award for best live act.
“This is amazing,” she said as she collected her award.
“I just played at this arena 10 days ago. This is my favourite award because my fans mean so much to me. I want to say it’s really easy to get a song — steal, download and listen — but it takes a commitment to go to a live show.”
US pop rockers LMFAO then performed their hit, Party Rocker Anthem.
After making a costume change, host Selena Gomez introduced presenter David Hasselhoff, who handed over the best female award to Lady Gaga.
Dressed in a bizarre fan-type dress with a black hat that covered her face, she said: “Thank you so much. I’m so grateful. I have had a lot of Botox and it is true.”
Katy Perry presented the global icon award to Queen.
Brian May, who received the award with Queen bandmate Roger Taylor said: “How wonderful for us to be here 40 years later. And how wonderful it is to be in Belfast, who is setting an example in the growth for true peace.”
Price Tag singer Jessie J said it was “humbling” to be nominated for two EMAs. She wowed on the pink carpet, wearing a leopard-print dress by Dolce & Gabbana.
Katy Perry, who was up for four awards including best single and best female, was a pink lady — matching the carpet by wearing a pink jacket and skirt, with hair in a similar tone.
Awards show host Selena Gomez wore a cream tulle Marchesa number as she arrived for the ceremony.
The women were almost upstaged by US pop duo LMFAO however, with one member wearing an animal-print jumpsuit with a giant zip and the other in a bodysuit.
Lady Gaga, Coldplay, Justin Bieber, Queen, Jessie J and David Guetta all performed at the ceremony.