Born in 1942 in Brooklyn, New York, Carol Klein (as she was then known) started out playing the piano and then moved on to singing, forming a vocal quartet called the Co-Sines in high school. While attending Queens College, King befriended Paul Simon, Neil Sedaka and Gerry Goffin.
Goffin and King soon formed a songwriting partnership, eventually marrying, working in the famous Brill Building, where chart-topping hits were churned out during the 1950s and early 1960s. The Goffin/King partnership first hit it big with "Will You Love Me Tomorrow", which topped the charts when released by the Shirelles in 1961. Future hits written by the pair include: "Take Good Care of My Baby" (Bobby Vee), "The Locomotion" (Little Eva), "One Fine Day" (The Chiffons), "Pleasant Valley Sunday" (The Monkees), "Up on the Roof" (The Drifters), "Chains" (The Cookies; later The Beatles), "(You Make Me Feel) Like a Natural Woman" (Aretha Franklin) and "He Hit Me (and It Felt Like a Kiss)" (The Crystals).
After failing several times at beginning a solo career, King eventually helped found a record label, Tomorrow Records, divorced Goffin and married Charles Larkey (of the Myddle Class). Moving to the West Coast, Larkey, King and Danny Kortchmar formed a group called the City, which released one album, Now That Everything's Been Said but the album was a commercial failure. King then released Writer (1970), another disastrous failure, followed by Tapestry (1971), her best known and most well-received album. One of the critical albums of the singer/songwriter genre of the early 1970s, Tapestry remains her most popular album among fans and critics. Music (1971), Rhymes and Reasons (1972) and Wrap Around Joy (1974) followed, each selling respectably.
Goffin and King reunited to write Thoroughbred (1975) with David Crosby, Graham Nash and James Taylor, a long-time friend of King's. She married another songwriting partner, Rick Evers, after releasing Simple Things (1977); he died of a heroin overdose one year later.
Retiring to Idaho, King became an environmental activist after releasing a collection called Speeding Time in 1983. She returned to music in 1989, recording City Streets, followed by Colour of Your Dreams (1993), with a guest appearance by Slash of Guns n' Roses.
Following the September 11, 2001 attacks, a list of approximately 150 songs circulated on the Internet, purported to be from radio conglomerate Clear Channel Communications to its subsidiaries, with the recommendation that these songs be pulled from airplay (it was later revealed that the list was originally the work of a few specific station program directors, was not an official Clear Channel missive, and changed over time as it was redistributed). King's tune "I Feel the Earth Move" was one of those listed.