She was born Katherine Laverne Starks on a reservation in Dougherty, Oklahoma. Her father, Harry, was a full-blooded Iroquois Indian; her mother, Annie, was of mixed Irish and American Indian heritage. When her father got a job installing water sprinkler systems, the family moved to Dallas, Texas. As a result of the fact that her aunt, Nora, was impressed by her singing, she began to sing at the age of seven on a Dallas radio station, WRR, first in a talent competition where she finished third one week and won every week thereafter, then with her own weekly 15-minute show. She sang pop and "hillbilly" songs with a piano accompaniment. By the age of 10, she was making $3 a night, a lot of money in the Depression days.

As a result of her father's changing jobs, her family moved to Memphis, Tennessee, and she continued performing on the radio, singing "Western swing music," still mostly a mix of country and pop. It was while she was on the Memphis radio station WMPS that, as a result of misspellings in her fan mail, she and her parents decided to give her the name "Kay Starr." At the age of fifteen, she was chosen to sing with the Joe Venuti orchestra. Venuti had a contract to play in the Peabody Hotel in Memphis which called for his band to feature a girl singer, which he did not have; Venuti's road manager heard her on the radio, and suggested her to Venuti. Because she was still in junior high school, her parents insisted that Venuti take her home no later than midnight. Although she had brief stints in 1939 with Bob Crosby and Glenn Miller (who hired her in July of that year when his regular singer, Marion Hutton, was sick), she spent most of her next few years with Venuti, until he dissolved his band in 1942. It was, however, with Miller that she cut her first record: "Baby Me"/"Love with a Capital You." It was not a great success, in part because the band played in a key more appropriate for Marion Hutton, which was, however, less suited for Kay's vocal range.

After finishing high school, she moved to Los Angeles and signed with Wingy Manone's band; then from 1943 to 1945 she sang with Charlie Barnet's band. She then retired for a year because she developed pneumonia and lost her voice as a result of fatigue and overwork.

In 1946 she became a soloist, and in 1947 signed a solo contract with Capitol Records. Capitol had a number of other female singers signed up (such as Peggy Lee, Ella Mae Morse, Jo Stafford, and Margaret Whiting), so it was hard to find her a niche. In 1948 when the American Federation of Musicians was threatening a strike, Capitol wanted to have all its singers record a lot of songs for future release. Since she was junior to all these other artists, every song she wanted to sing got offered to all the others, until finally he put out a list of old songs from earlier in the century, which nobody else wanted to record.

Around 1950 she made a trip back home to Dougherty and heard a fiddle recording of Pee Wee King's song, "Bonaparte's Retreat." She liked it so much that she wanted to record it, and contacted Roy Acuff's publishing house in Nashville, Tennessee. She spoke to Acuff directly, and he was happy to let her record it, but it took a while for her to make clear that she wasn't a fiddler, but a singer, and she needed to have some lyrics written. Eventually Acuff came up with a new lyric, and "Bonaparte's Retreat" became her biggest hit up to that point, coming close to a million sales.

In 1955, she signed with RCA Victor Records. However, at this time, traditional pop music was being superseded by Rock and roll, and Kay had only one hit, which is sometimes consifered her attempt to sing R'n'R and sometimes as a song making fun of R'n'R: "The Rock and Roll Waltz." She stayed at RCA Victor until 1959, then returned to Capitol.

Most of her songs have jazz influences, and, like Frankie Laine and Johnnie Ray, are sung in a style that sound decidedly close to the rock and roll songs that follow. These include her smash hits "Wheel of Fortune" (her biggest hit, #1 for 10 weeks), "Side by Side," "The Man Upstairs," and "Rock and Roll Waltz." One of her biggest hits was her version of "The Man with the Bag," a Christmas song, which can be heard nonstop every holiday season in stores, restaurants, and on the radio.