"SexyBack" is an "urgent, pulsing track, a cocktail of soaring, distorted vocals and heavy, electronic chords threaded together with rap", according to Camilla Long from "The Observer". The song is composed in the key of A major — and is set in time signature of common time with a tempo of 117 beats per minute. The song features a pounding bass beat and electronic sounds, and does not include Timberlake's "famous falsetto". The song's musicscape includes two-note dirty electronic riffs, "leapfrogging keyboards", beat box sound, and incorporates the "same leaky faucet" sounds of musician Obie Trice's 2004 song "The Setup". In addition, the track features Timbaland on backing vocals.