The singer joined Taylor on stage for rendition of his hit ‘Angels’, as she played her latest show at Wembley Stadium.
Fans were blown away by the performance, which was hailed as a real “moment” on social media.
However, it is not the first time she has brought on a surprise guest during her ‘Reputation’ tour.
On Friday, former One Directioner Niall Horan came out to duet on his single ‘Slow Hands’ with her.
Taylor’s tour has made a number of headlines since it kicked off at the start of May, initally surrounding the huge snake statues the set features, in reference to her feud with Kim Kardashian and Kanye West.
More recently, she was hit by reports of poor ticket sales for her UK stadium shows, which has been blamed on high ticket prices.
Meanwhile, Robbie is said to be gearing up for a judging role on ‘The X Factor’.
It has been rumoured he and wife Ayda Field will be joining the panel for the show’s 15th series later this year, replacing the departing Nicole Scherzinger and Louis Walsh.
While nothing has yet been confirmed, Robbie remained coy about the claims during an appearance on ‘This Morning’ last week.
He said: “If there is an ‘X Factor’ in my future, whether it be this year or next year or never, I’m scared for my own safety and health but not because of the people out there, the public, Twitter or Instagram, my wife. She is an A+ student from Beverly Hills, incredibly square, she is like ‘why would you do that?’
“She is supposed to be doing it with me. I have read those reports too. I would say…as it happens people say that every year and we say ‘no comment’. Yeah, there is a lot of me that would love to do it too. But as it happens, people are talking nothing has been signed. But watch this space.”