June Christy was born Shirley Luster on November 20, 1925, in Springfield, Illinois, to Steve and Marie Luster, and grew up from the age of three in Decatur. At thirteen she began singing with the Decatur-based Bill Oetzel Orchestra, and through high school she also appeared with the Ben Bradley Band and Bill Madden's band. Her first work outside Decatur was with the Dick Cisne Orchestra of nearby Champaign, which took her as far as Texas and Louisiana. After high school she moved to Chicago, worked briefly under the name Sharon Leslie, and sang with a group led by Boyd Raeburn and then with Benny Strong's band. When Strong's band moved to New York in 1944, she was quarantined in Chicago with scarlet fever and stayed behind.

In 1945, after Anita O'Day left the Stan Kenton Orchestra, Luster auditioned for the vacancy and was hired, taking the name June Christy. Her first record with the band was "Tampico," which she later said she had been disappointed to begin with, though its success established her at once; it became a million-seller and the biggest-selling record of Kenton's career. "Shoo Fly Pie and Apple Pan Dowdy" and "How High the Moon" followed. She sang on the Kenton albums Artistry in Rhythm, A Presentation of Progressive Jazz, Encores, Innovations in Modern Music (1950), and Stan Kenton Presents (1950), among others. She married the orchestra's tenor saxophonist Bob Cooper in 1947. When the Kenton band broke up temporarily in 1948 she worked nightclubs for a short time, and she rejoined it two years later.

From 1947 she also made records under her own name, mostly with Kenton's chief arranger Pete Rugolo. Her breakthrough as a solo artist was Something Cool, recorded in seven sessions between August 1953 and March 1954 with Rugolo arranging and conducting a Los Angeles band that included Cooper, altoist Bud Shank, drummer Shelly Manne, and trumpeter Shorty Rogers. Capitol issued it in August 1954 as a 10-inch LP of seven songs; it reached number 8 on Billboard's best-selling albums chart in the week of January 8, 1955. A 12-inch LP with eleven songs followed in August 1955, and Christy and Rugolo re-recorded all eleven in stereo on April 26 to 28, 1960, a version that was the only one in print for many years. She called it the only record she had made that she was not unhappy with. Her daughter, Shay Christy Cooper, was born on September 1, 1954.

The next decade was her most productive. She cut the duo album Duet with Kenton alone at the piano in May 1955, then a run of Rugolo-arranged Capitol albums: The Misty Miss Christy (1956), Fair and Warmer! (1957, number 16 on Billboard's pop chart), and Gone for the Day (1957), followed by The Song Is June! and Off-Beat. Cooper arranged and conducted June's Got Rhythm (1958) and Ballads for Night People (recorded in August and September 1959), and in January and February 1959 Rugolo conducted a band of Kenton alumni on June Christy Recalls Those Kenton Days, in which she re-recorded the songs she had sung with the orchestra. On September 28, 1959, she began a five-week, 38-performance tour called Road Show, billed with the Kenton orchestra and the Four Freshmen; Capitol recorded the October 10 concert at Purdue University for a two-LP set. Later Capitol albums included The Cool School (1960, children's songs with the Joe Castro Quartet, with her five-year-old daughter on the cover), Do-Re-Mi (1961, with Cooper), her only Christmas album, This Time of Year (1961), Big Band Specials with charts by Bill Holman, Shorty Rogers and Cooper, The Intimate Miss Christy (1963), and Something Broadway, Something Latin (1965, with Ernie Freeman).

Christy also made many television appearances, from The Jackie Gleason Show (1953) and The Tonight Show (1955) to The Nat King Cole Show (1957) and The Steve Allen Show (1959). On December 30, 1957, she appeared on the Timex All-Star Jazz Show, the first sponsored jazz concert on television, alongside Louis Armstrong, Carmen McRae, Duke Ellington, and Gene Krupa. She played Europe, South Africa, Australia, and Japan, but the touring strained her marriage, and by the 1960s she had pulled back from the road.

She semi-retired in 1969, partly because of alcoholism. In 1972 she sang at the Newport Jazz Festival in New York and was reunited with the Kenton orchestra, and in the late 1970s and 1980s she appeared at a handful of festivals with an all-star West Coast band led by Shorty Rogers. In June 1977 she recorded Impromptu, her last solo album, with a Lou Levy sextet that included trumpeter Jack Sheldon, trombonist Frank Rosolino, Cooper, and Manne. She toured one last time in 1985 with Rogers, and her final performance was on a bill shared with Chet Baker. Christy passed away at her home in Sherman Oaks, California, on June 21, 1990, of kidney failure, at 64. After her death she was widely described as one of the finest and most neglected singers of her era.

Christy sang with a clear, cool, lightly vibrato-shaded tone that critics heard as wholesome and sensuous at once; The Penguin Guide to Jazz Recordings described her as less an improviser than a singer of long, controlled lines, and named "Something Cool," "Midnight Sun," and "I Should Care" among her definitive readings. The jazz writer John Bush credited Something Cool with launching the cool movement in jazz singing, and Will Friedwald called it closer to a perfect album than most records by better-known jazz singers, naming Anita O'Day and Ella Fitzgerald. She came up through the Stan Kenton orchestra's brass-heavy, modernist book, where she replaced O'Day, whose horn-like phrasing is credited with influencing her, and her solo records with Rugolo and Cooper took that West Coast sound into small-group and chamber settings of woodwinds, strings, and rhythm section. The same long, controlled lines suited ballads, while June's Got Rhythm and Big Band Specials put her in swinging settings. Her music sits at the meeting point of big-band vocals, cool jazz, and West Coast studio jazz, and the standards she chose, by Duke Ellington, Rodgers and Hart, Harold Arlen, and Billie Holiday, kept her work firmly in the jazz repertoire.