Posting the picture in honour of National Best Friends Day, the "Bad Blood" singer called the DJ her "favourite" person, reported Ace Showbiz.
The black-and-white picture was posted by Swift's friend Gigi Hadid on her own Instagram. It features the model, Harris and Swift's other close friend Karlie Kloss having fun while laughing in a kitchen.
Hadid captioned the image, "There's not a picture that could fit in everyone that I appreciate, but this post is dedicated to all the friends that light up my life - you know who you are. I'm the luckiest."
She accompanied the post with a sweet message that read, "I took a photo of my favourite people - they were laughing so hard, the lens couldn't capture it fast enough."
Swift and Harris, 31, have been romantically linked since March when they were seen together at the 2015 Brit Awards. Although they haven't addressed publicly their blossoming romance, people strongly believe that they are dating after the pair were seen kissing and hugging on camera at the 2015 Billboard Music Awards.