Swift told fans before introducing the pop legend: “I wanted to sing a song that you all knew the words to.”
The pair sang a duet of Robbie’s most popular track ‘Angels’.
Robbie sported a Taylor Swift t-shirt while singing the classic with the star to a packed out stadium.
The crowd, which had already been treated to performances by supporting acts Charlie XCX and Camilla Cabello, filled social media with pictures and videos of the duo.
One fan, Joshua Fox, tweeted: “Taylor Swift ft Robbie Williams at Wembley Stadium just then was everything I never knew I wanted from a gig.”
Robbie later shared a photo of them together with the caption: “What an honour to sing with you tonight @taylorswift13 I’ve got a proper crush. THANK YOU THANK YOU THANK YOU x”
Taylor, who was once known for standing alone on stage with a guitar, took it up a notch on her Reputation tour.
The show kicked off to hit song ‘Are You Ready For It’ as red lighting flooded the stage and dancers swung from a trapeze.
Later, making use of the arena, Swift used wires to transport herself above the crowd not once but twice.
Pyro technics, confetti, snakes and outfit changes were all common place during and in between performances of hit song after hit song.
Die-hard Taylor fans weren’t left disappointed either as Swift performed, ‘Love Story’ and ‘Fifteen,’ from her album ‘Fearless’ which propelled the singer to stardom in 2008.
While Taylor’s latest tour has proved to be the biggest show on the 2018 pop calendar, fans originally complained about ticket prices.
One fan Hannah Curry tweeted the Taylor saying: “Hey @taylorswift13, I’m so disappointed. Your ticket prices are unreasonable and your fans have to watch you from the back / not go at all.”
Fans that dig bag themselves a seat seemed to agree however, that it’s definitely worth paying the price to see Taylor when she comes to town.