Riley was born in 1945 in Stamford, Texas. As a teenager, she married Mickey Riley and gave birth to a daughter, Kim Michelle Riley on January 11, 1966. Later, they moved to Nashville, Tennessee after receiving a letter from Weldon Myrick, who heard a demo tape of Jeannie's and believed she could be successful. In Nashville, Riley worked as a secretary for Passkey Music while recording demos on the side.
Riley's career was stagnant until former Mercury Records producer Shelby Singleton received a demo tape of Riley's voice. Singleton was starting and succeeding with his own label, Plantation Records, at the time. He worked with Riley in the recording of the Tom T. Hall demo song that Singleton saw potential in, "Harper Valley PTA." The record quickly became one of the best-known country music songs of all time.
"Harper Valley PTA" was released in 1968. The song immediately became a hit for Riley and went to number one on both the Billboard Pop and Country charts, a feat not repeated by a woman until 1981 when Dolly Parton released "9 to 5". The song is about a widowed woman by the name of Mrs. Johnson, who confronts a group of members of the PTA after her daughter brings home a note from school that is critical of her (Mrs. Johnson's) habits of wearing miniskirts, going out with men, and other behavior of which they do not approve. The climax of the song comes when Mrs. Johnson turns the tables on the PTA and exposes their hypocrisy, one member at a time, noting that their private behavior is far worse than what their letter criticized her for.
Riley and the song became an overnight sensation, and the song earned her the Grammy Award for Best Female Country Vocal Performance and the Country Music Association 'Single of the Year' award. Riley also became one of the few country artists ever nominated in the major pop Grammy Award categories of "Best New Artist" and "Record of the Year". Globally it sold over five and a half million copies, and was awarded a gold disc by the R.I.A.A. just four weeks after the song's release. The album of the same name sold over one million units to gain a further gold disc for Riley.
The song was a phenomenon which led to Riley making country music history in 1969 as the first female vocalist to have her own major network variety special, Harper Valley U.S.A., which she hosted along with Jerry Reed and featured performances by Mel Tillis and the song's writer, Tom T. Hall.
The song spawned a 1978 film and a 1981-83 television series, both titled Harper Valley PTA and both starring Barbara Eden as the widow Mrs. Johnson.
During the late 1960s and into the very early 1970s, Riley ranked among the most popular female vocalists in the country music industry. She had five Grammy Award nominations and four Country Music Association nominations, and performed a duet with Loretta Lynn. She had success on the country charts again, but on a lesser scale.
Other hits following "Harper Valley PTA" include "The Girl Most Likely," "There Never Was A Time," "The Rib," "The Back Side of Dallas," "Country Girl," "Oh Singer," and "Good Enough to Be Your Wife."
Riley became known as much for her sex appeal and beauty as for her music, foreshadowing Shania Twain and other contemporary female vocalists by nearly three decades. At a time when many country queens were keeping a wholesome image by wearing gingham dresses, Riley kept in tune with typical late-1960s fashion by donning miniskirts and go-go boots for her stage outfits. Her mod persona opened many doors (and perhaps started a sexual revolution) in country music, as hemlines of other female country artists' stage outfits began rising in the years since. But Riley herself was not comfortable with her image, and she eventually abandoned it for a more conservative wardrobe. In the 1993 CBS documentary The Woman of Country, she noted that during the "Harper Valley" period, it was largely her publicist and manager who were responsible for creating and playing up her sexy image (replicating somewhat the look of the protagonist in the song).
Riley's great success brought a number of offers from Hollywood, and she appeared with Bing Crosby, Dean Martin, Bette Davis, Tom Jones, Ed Sullivan and others on various television programs.
Riley left Plantation Records for MGM Records in 1972, recording several albums, but only two of her singles from the period, "Good Morning Country Rain" and "Give Myself A Party," cracked the top 30. Later stints at Mercury Records and Warner Bros. Records produced only a couple of charted singles, but Riley remained highly in demand as a concert artist well into the 1980s.
In the 1970s, she became a Born Again Christian and began recording gospel music. As result of her conversion, she distanced herself from "PTA" for a time, due to its content. However, the song remained part of her live set and she still performs it in her shows. In 1980, she published her autobiography, From Harper Valley to the Mountain Top, which told her story of stardom in pop music to moving more into gospel music. The following year, she released a new gospel album with the same title.A "Harper Valley PTA" was certified Gold by the RIAA. "Harper Valley PTA" also made the Adult Contemporary Charts, hitting #4. In the UK, it went to #12 Pop.