The pair will sing their duet Everything Has Changed, which they co-wrote for Taylor's latest album Red.
Also set to perform during the show is Youtube sensation Psy.
Following the massive global success of his debut single Gangnam Style; the South Korean pop star will be exclusively singing his new track Gentlemen.
Ten acts are set to perform during the live final, including Northern Ireland singer Jordan O'Keefe.
Speaking about the upcoming show, the 19-year-old said: "I'm really excited. I'm trying to keep level headed but no words can describe what it feels like to be in the BGT final.
Jordan impressed the judges during last Saturday's semi-final following his acoustic rendition of Dolly Parton's classic I Will Always Love You.
"I chose to sing a female artist's song with my own arrangement because I wanted to stand out," said Jordan.
"I don't want to go back to what I was doing before - I don't think I am going to win but I'm going to do my best. I want to be in the top three.
"I think Luminites and Attraction are my biggest competition - Luminites in particular because they are also musical."
One more act from the semi-finals, yet to be announced by the judges, will take part as a "wildcard" finalist during Saturday's show.
The Britain's Got Talent final will air on UTV on Saturday 8 June at 7.30pm.