Whiting was born in Detroit, but her family moved to Los Angeles in 1929, when she was five years old. Her father, Richard, was a composer of popular songs, including the classics "Hooray for Hollywood", "Ain't We Got Fun?", and "On the Good Ship Lollipop". Her sister, Barbara Whiting, was an actress (Junior Miss, Beware, My Lovely) and singer.
An aunt, Margaret Young, was a singer and popular recording artist in the 1920s. In her childhood, Whiting's singing ability had already been noticed, and at the age of only seven she sang for singer-lyricist Johnny Mercer, with whom her father had collaborated on some popular songs ("Too Marvelous for Words"). In 1942, Mercer co-founded Capitol Records and signed Margaret to one of Capitol's first recording contracts.
Whiting's first recordings were as featured singer with various orchestras:
In 1945, Whiting began to record under her own name, making such recordings as:
Until the mid-1950s Whiting continued to record for Capitol, but as she ceased to record songs that charted as hits, she switched to Dot Records in 1957 and to Verve Records in 1960. Whiting returned to Capitol in the early 1960s and then signed with London Records in 1966. On London, Whiting landed one last major hit single in 1966, "The Wheel of Hurt", which hit #1 on the Easy Listening singles chart. Her final solo albums were made for Audiophile (1980, 1982, 1985) and DRG Records (1991). Her distinguished conductors and musical arrangers through the years included Buddy Bregman, Frank DeVol, Russell Garcia, Johnny Mandel, Billy May, Marty Paich, Nelson Riddle, Pete Rugolo, and Paul Weston.
Whiting co-starred on the 15-minute musical programs The Jack Smith Show and Club Fifteen. She also was a vocalist on The Eddie Cantor Show and was in the cast of The Philip Morris Follies of 1946 and The Railroad Hour. Additionally, she was hostess on the Spotlight Revue and a featured singer on the transcribed Barry Wood Show. She also appeared in the part of a young Sophie Tucker, in the Lux Radio Theater production "No Time For Heartaches".
Margaret and Barbara Whiting starred as themselves in the situation comedy Those Whiting Girls. The show, produced by Desilu Productions, aired on CBS as a summer replacement series (in place of I Love Lucy) between July, 1955 and September, 1957.