This song finds the Sofi Tukker duo of Sophie Hawley-Weld and Tucker Halpern celebrating friendship. They explained:

"It's about the kind of friendship where you can talk forever without anything in particular to talk about. Old friends, new friends, all friends! In the spirit of friendship, we just wanted to have some of our friends hop on a verse! We've been lucky enough to travel the world this past year and the best part of the journey is the friendships we have made and the friendships we have been lucky enough to revisit along the way. We (Soph and Tuck) have also become each other's best friend over the past few years, and we are so grateful to each other!"

The song features several of Sofi Tukker's friends, namely Alisa Ueno, The Knocks and NERVO. Tucker said:
"Our friendship with The Knocks is what gave us the confidence to pursue a career in music, thank you Broc and Jpatt! NERVO, newer friends, inspire us and motivate us to push ourselves and be relentlessly positive, thank you Mim and Liv! Alisa Ueno is a brand new friend who we share a ton of mutual friends with and we are also building a new friendship with Japan."

The song soundtracked Apple's unveiling of the iPhone X. Previous Apple ads have used tracks by the likes of The Black Eyed Peas, Feist and The Ting Tings. Tucker Halpern told Billboard how the placement came about.

"We had a pretty juicy relationship with the music director at Apple, because he sort of discovered us and put us on that Apple watch commercial back when we started [in 2015]. We sent him all the new music we've been working on and they got back to us like, "We think we want to do something big around 'Best Friend.'" And we were like, 'What?! Maybe we should put that out as a single.'"

The video was directed by filmmaker Mac Boucher a.k.a. the brother of the Canadian musician Grimes.