"Yummy" is a "straightforward R&B number" that moves along on pop-trap beats. The song contains a "crisp bass line and plinking keyboards". Bieber rap-sings the pre-chorus, while he hits his "signature falsetto" in the bridge. Bryan Rolli of "Forbes" magazine called the chorus "seductive", albeit "meaningless". The song is considered an ode to Bieber's wife, Hailey Bieber.