Shawn Mendes and Camila Cabello Perform 'I Know What You Did Last Summer' at the 2016 People's Choice Awards

Camila Cabello and Shawn Mendes
Jeff Kravitz/FilmMagic

Camila Cabello and Shawn Mendes perform during the People's Choice Awards 2016 at Microsoft Theater on January 6, 2016 in Los Angeles, California.

Shawn Mendes and Fifth Harmony's Camila Cabello thrilled fans when they performed "I Know What You Did Last Summer," the song they co-wrote together, at Wednesday night's 2016 People's Choice Awards at the Microsoft Theater in Los Angeles. Mendes started the performance with an acoustic solo rendition of his hit single "Stitches," singing before a rainstorm backdrop before Cabello joined him onstage for their heated duet.

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Mendes was a People's Choice nominee this year in the Favorite Breakout Artist category, an honor he won earlier in the night, while Cabello's girl band was among the nominees for Favorite Group. The single they performed together was the result of the friendship between the two performers that blossomed backstage at a Taylor Swift concert last year. It was featured on Mendes' debut album Handwritten Revisited and dropped on Nov. 17 after days of hinting by the stars over social media.

Shawn Mendes and Camila Cabello's Duet 'I Know What You Did Last Summer' is Here

Watch their performance below!

Amazing! @ShawnMendes and @camilacabello97 put on an amazing performance. #PCAs

— People's Choice (@peopleschoice) January 7, 2016