Taylor unexpectedly brought out Cher as her special guest, which led the crowds to go wild as the pair joined forces to sing Cher's 2012 hit, 'Want U Back'.
Introducing the former X Factor star to the audience at the Staples Centre, Taylor spoke about how much the song had influenced her.
"She is a long way away from home," she said. "She sings this song that has been in my head ever since it came out last summer.
"I know you probably know it; the feeling that when you break up with somebody and then you're like, 'Ugh, I shouldn't have done that. I want you back'."
Cher, who showed off her glamorous bob which she unveiled at the Teen Choice Awards earlier this month, wore a leather panel mini dress as she made her way down the stage stairs. Meanwhile, Taylor showed off her legs in fitted red shorts.
After the performance, the pair couldn't stop complimenting each other and even posed for a cute photo backstage.
X Factor alumni Cher said: "Had the most amazing time performing with @taylorswift13. She's the sweetest girl I've ever met!!! Loved it!!! Xxx."
Taylor added: "One of my favourite moments of the night was @CherLloyd coming out to sing 'Want U Back'. The crowd went insane!! And she's such a fun girl!"
Check out Taylor Swift and Cher Lloyd performing 'Want U Back' below: