The 18-year-old Fifth Harmony member and 17-year-old “Stitches: singer will be performing their hit duet “I Know What You Did Last Summer,” so be sure to check back to JJJ for all the pics and video.
Meanwhile, Camila can’t hold in her excitement. She posted a cute video on Instagram, which you can see below!
“omg @shawnmendes. @jimmyfallon,” Camila captioned the video.