The song’s lyrics see the trio celebrate their friendship through themes of love and loyalty. “We will always be as one,” they sing. “So here’s my vow, starting from here and now, nothing comes between us.” All three of the band’s members have writing credits on the track alongside MNEK, Tre Jean-Marie and Janee ‘Jin Jin’ Bennett. “Between Us is basically the song that we’re never going to be able to get through live,” Perrie Edwards said. “We’re going to be in floods of tears in front of everyone.
It’s just such a cute stunning song, I love it so much.” The lyrics to Between Us feature subtle references to the group’s previous hits such as Power and Sweet Melody.