Garrett first met Wonder at the Michigan School for fhe Blind. The two began writing songs together with the first fruit of their collaboration being the Spinners' 1968 Motown number four R&B hit "It's a Shame." "Signed, Sealed and Delivered I'm Yours," co-written by Garrett, Wonder, Syreeta Wright (who had a Motown number four pop hit duet with Billy Preston, "With You I'm Born Again"), and Lula Mae Hardaway, held the number one R&B spot for six weeks and went to number three pop on Billboard's charts in summer 1970. The Signed, Sealed Delivered I'm Yours LP peaked at number 25 pop in fall 1970.

In 1976, Garrett signed to Chrysalis and had a moderate R&B hit with "You're My Everything," taken from his lone solo album, Heat for the Feets. Back with Stevie Wonder, he wrote the kinetic "Let's Get Serious" for Jermaine Jackson, which parked at number one R&B for six weeks and hit number nine pop in spring 1980. The Let's Get Serious album went gold, going to number six pop in summer 1980. ~ Ed Hogan