“Sucker” is an upbeat pop song, and the band’s first single in almost six years. The brothers collectively portray someone who is infatuated with someone and for whom they would go to great lengths. The light rock instrumentation throughout the track is minimal, leaving the central focus on the brothers' vocals on their comeback single.

The song was teased in a YouTube video released by The Late Late Show with James Corden and was officially confirmed through a Twitter post: