Celestine Sibley was born in Holley, Florida, on May 23, 1914, to Evelyn Barber and Henry Colley. Sibley's mother, later known as "Muv" in Sibley's column, left her father (though she never officially divorced him) and married Wesley Reeder Sibley, a lumberman from Creola, Alabama. Adopted by her stepfather at the age of seven, the young Celestine was given his last name and spent her childhood in Creola, a small town on the outskirts of Mobile. At age fifteen, Sibley, an ambitious student reporter at Murphy High School's Hi Times, was hired as a weekend cub reporter at the Mobile Press Register. When she graduated in 1933, Sibley was offered her first full-time paid position at the Press. Covering everything from welfare to murder, the young journalist earned priceless experience at the Press, while her natural talent and attention to detail established her as a solid writer from the beginning of her career.

In 1936 she and her husband, Press colleague and journalist James W. Little, moved to Pensacola, Florida. Sibley began writing for the Pensacola News-Journal and continued to cover all aspects of local news. In the summer of 1941, her husband accepted a position with the Associated Press in Atlanta and moved the family there.

Sibley began working at the Atlanta Constitution on July 21, 1941, assigned to the federal beat. Less than six months later, Pearl Harbor was attacked, and the United States entered World War II (1941-45). The resulting staff depletion provided an unprecedented opportunity for Sibley...she became one of the first female editors at the Constitution, working under the tutelage of Ralph McGill, whom she later described as her mentor. Competent yet restless in her newly assigned desk position, Sibley still preferred to be a "member of the ground troops" with a natural inclination to cover the stories on the street.

Sibley was given her first column in 1944, which allowed her more time to be with her children. Both full-time reporter and mother, Sibley was still able to become a front-page news and courtroom reporter, covering the three governors controversy in 1946 as well as many high-profile trials. In 1947 her investigative coverage of police and political corruption surrounding a murder case resulted in the acquittal of convicted murderer Floyd Woodward, and she later received the Hartsfield and Sibley Pall Mall Big Story award, given by NBC for the best story of the week, for her coverage of the case. The following year she covered the murder trial of John Wallace, which later became nationally known through the publication of Margaret Anne Barnes's best-selling book Murder in Coweta County (1976), as well as through the adaptation of the book into a television movie in 1983 starring Johnny Cash and Andy Griffith.

In the early 1950s, Sibley worked for five years as the Hollywood correspondent for the Sunday Atlanta Journal and Constitution Magazine, traveling to Los Angeles, California, and interviewing movie stars and filmmakers. Her profiles, which she later called "fluff stories," included such celebrities as Clark Gable, Walt Disney, and Jane Russell. "Pulp stories" also became an infamous part of Sibley's versatile writing career during this time. As another creative way to support her family, Sibley moonlighted as a True Confession and True Detective reporter, selling stories with such shocking headlines as "I Wanted to Die" and "I Was a Junkie."

Her short-lived pulp career was eventually replaced by a long-term book career, beginning with the publication of The Malignant Heart (1958), the first book in the Kate Mulcay mystery series. For nearly forty years, Sibley continued to publish books in a variety of genres, including Peachtree Street, U.S.A. (1963), a portrait of Atlanta; Dear Store (1967), a history of Rich's Department Store; A Place Called Sweet Apple (1967), reflections on restoring her log cabin home in Roswell; Jincey (1978), her first novel; Turned Funny (1988), her memoir; and additional installments in the Kate Mulcay series. In 1982 her novel Children, My Children won the first Townsend Prize for children's fiction.

From 1958 to 1978 Sibley covered politics, courts, and the Georgia legislature, including the annual forty-day Georgia General Assembly, which became one of her favorite assignments. Sibley's legislative reporting was considered fair, unbiased, and accessible to the general public. During these years she also reported on the trial of James Earl Ray, who was convicted of assassinating Martin Luther King Jr. in 1968, and on the 1976 presidential election, in which Jimmy Carter became the first Georgian elected president of the United States. As a gesture of appreciation for her years of excellent political reporting, the United States House of Representatives voted in 2000 to name its press gallery at the state capitol in Sibley's honor.

Although Sibley spent the bulk of her career as a reporter, she is perhaps best remembered as a syndicated columnist for the Atlanta Constitution. Even after she retired from reporting in the late 1990s, Celestine Sibley continued to spend the majority of her days writing books, as well as continuing her columns about southern life. In 1990 she received the Ralph McGill Award for Lifetime Achievement in Journalism. She also received two honorary degrees during her career, one in 1993 from Spring Hill College in Mobile, Alabama, and another in 1996 from Emory University in Atlanta. A few months before her death, Sibley was awarded the National Society of Newspaper Columnists Lifetime Achievement Award.

Sibley died of cancer at the age of eighty-five on August 15, 1999. She continued working until the final weeks before her death, with her last regular Constitution column appearing on July 25, 1999.

Sibley's first husband died at age forty-five; they had three children together. Her second husband, John C. Strong, died in 1988.

Sibley is the subject of a play, Turned Funny, adapted from her 1988 autobiography of the same name by Phillip DePoy. The play premiered at Theatre In the Square in Marietta, Georgia in 2006 and was re-produced from June 17 to July 29, 2007. For both runs Celestine Sibley was played by Linda Stephens.