She was born Myra Belle Shirley near Carthage, Missouri into a farming family. Her family moved to Carthage in the 1860s and her father became an inn owner. After the Union attack on Carthage in 1864 the Shirleys moved to Scyene, Texas. At Scyene the Shirleys became associated with a number of Missouri-born criminals, including Jesse James and the Youngers. After a relationship with Cole Younger she married Jim Reed, another outlaw, in 1866 and gave birth to her first child in 1868. With Jim wanted for murder the family moved to California, where their second child was born in 1871. Returning to Texas Jim worked with a number of criminal gangs. In April 1874, despite a lack of evidence, a warrant was issued for her arrest over a stage coach robbery carried out by her husband and others. Jim was killed in Paris in August of that year.
In 1878 she was briefly married to Bruce Younger, in 1880 she married Sam Starr. In 1883 she was charged with horse theft in Arkansas and went to trial before Judge Isaac Parker, found guilty she served six months at the federal prison in Detroit, Michigan. In 1886 she escaped conviction on another theft charge, but Sam Starr was shot and killed in December, possibly in a drunken brawl.
After Starr she associated with several men, almost all of whom died violently. In 1889 she was killed herself by parties unknown. Although an obscure figure at the time of her death, her story was picked up the reporter Richard K. Fox. He made her name famous with the largely fictional novel Bella Starr, the Bandit Queen, or the Female Jesse James, published in 1889. It was the first of many popular stories that used her name.