The track was co-written by Harris and Smith along with Jesse Reyez. "Promises" follows the 34-year-old producer's previously released 2018 tracks including "Nuh Ready Nuh Ready" and "One Kiss."
"I make no promises, I can't do golden rings / but I'll give you everything (tonight) / magic is in the air, there ain't no science here / so come get your everything (tonight)"
Both Calvin Harris and Sam Smith appear in the lyric video for "Promises" below. The song marks the first collaboration to ever be released by the pair.