Tammi Terrell began recording for Scepter/Wand Records at the age of 15, before touring with the James Brown Revue for a year. In 1965, she married heavyweight boxer Ernie Terrell, the brother of future Supreme Jean Terrell. Terrell's warm, sensuous vocals won her a contract with Motown Records later that year, and in 1966 she enjoyed a series of R&B hits, among them a soulful rendition of "This Old Heart Of Mine". In 1967, she was selected to replace Kim Weston as Marvin Gaye's recording partner. This inspired teaming produced Gaye's most successful duets, and the pair issued a stream of hit singles between 1967 and 1969. "Ain't No Mountain High Enough" and "You're All I Need To Get By" epitomized their style, as Gaye and Terrell wove around each other's voices, creating an aura of romance and eroticism that led to persistent rumours that they were lovers.

From the beginning, their partnership was tinged with unhappiness, Terrell collapsing in Gaye's arms during a performance in 1967. She was diagnosed as suffering from a brain tumour, and despite a series of major operations over the next three years, her health steadily weakened. By 1969, she was unable to perform in public, and on several of the duo's final recordings, their producer, Valerie Simpson, controversially claims to have taken her place. Ironically, one of these tracks, "The Onion Song", proved to be the most successful of the Gaye/Terrell singles in the UK.

Tammi Terrell died on 16 March 1970, her burial service attracting thousands of mourners, including many of her Motown colleagues.