Blanco was born on 15 February 1943 on the north coast of Colombia, and moved to Medellín when she was three years old. In the film Cocaine Cowboys II: Hustlin' with the Godmother Blanco's former lover, Charles Cosby, recounts how Griselda, at age 11, allegedly kidnapped, tried to ransom and eventually shot a child from the upscale flatland neighborhood near her hillside slum neighborhood. By her preteens, she had become a pickpocket, and at the age of 14 she ran away from her physically abusive mother and resorted to prostitution for a few years in Medellín.
In the mid-1970s, Blanco and her second husband, Alberto Bravo, emigrated to the United States, settling in Queens, New York City. They established a sizable cocaine business there, and in April 1975, Blanco was indicted on federal drug conspiracy charges along with 30 of her subordinates, at that time the biggest cocaine case in history. She fled to Colombia before she could be arrested, but in the late 1970s she returned to Miami.
Blanco was involved in much of the drug-related violence known as the Cocaine Cowboy Wars that plagued Miami in the late 1970s and early 1980s, when cocaine supplanted marijuana. Her distribution network, which spanned the United States, brought in US$80 million per month. Blanco's violent business style brought government scrutiny to South Florida, leading to the demise of her organization and the free-wheeling, high profile Miami drug scene of those times. She is suspected of having masterminded over 200 murders during this time in Dade County.
In 1984, Blanco's willingness to use violence against her Miami competitors, or anyone who displeased her, led her rivals to make repeated attempts to kill her. She moved to California to escape the assassination attempts. On 20 February 1985, she was arrested by DEA agents in her home. Held without bail, Blanco was sentenced to more than a decade in jail. She continued to run her cocaine business while in jail. By pressuring one of her lieutenants, the Miami-Dade State Attorney's Office obtained sufficient evidence to indict her for three murders. However, the case collapsed, largely due to technicalities and Blanco was released from prison and deported to Colombia in 2004.
The out of control gang related violence that became known as the Cocaine Cowboy Wars during the cocaine boom in Miami (as described in the Cocaine Cowboys documentary) had Griselda Blanco behind it most of the time. She is believed to have masterminded more than two hundred murders in the United States.
Blanco became the Godmother of the cocaine industry; her network spread across the U.S., bringing in $80 million a month. Blanco created many of the smuggling techniques and murdering methods that are still used today. Not only was she involved in the trade, but she played a huge role in the Cocaine Cowboy Wars that plagued Miami. She was ruthless against rival drug traffickers, and was the mastermind behind hundreds of murders. Colombian officials suspect that she was involved in at least 250 murders in their country, and U.S. detectives believe she is responsible for 40 deaths in America.