Vollmer was born in New Orleans to German immigrant parents, John and Philopine (Klundt) Vollmer. His father saw to it that he learned to box and swim, both of which he excelled at. Upon his father's death, his mother returned to Germany with her children for two years, after which she returned to New Orleans in 1886, but soon thereafter decided to move her family to San Francisco. In July 1890, the Vollmer family moved across the bay to Berkeley.
Before he was 20, August helped organize the North Berkeley Volunteer Fire Department, and in 1897, was awarded the Berkeley Fireman medal. He supported his mother and the rest of his family as a partner in Patterson and Vollmer, a hay, grain, wood and coal supply store, at the corner of Shattuck Avenue and Vine Street near a fire station north of downtown Berkeley.
In 1898, August enlisted in the United States Marines, fighting in 25 battles in the Spanish–American War in the Philippines. Vollmer left the military in August 1899 and returned to Berkeley. In March 1900, he began working for the local post office.
In 1904, he won fame as a local hero after he leapt onto a runaway railroad freight car on Shattuck Avenue in downtown Berkeley and applied its brakes, preventing a disastrous collision with a passenger coach loaded with commuters at the Berkeley station. This event led to his election as town marshal on April 10, 1905.
In 1907, Vollmer was re-elected town marshal. He was also elected president of the California Association of Police Chiefs, even though, by title, he was not yet a police chief himself. In 1909, Berkeley created the office of police chief, and Vollmer became the first to hold that office.
Drawing on his military experience, and his own research, Vollmer reorganized the Berkeley police force. Vollmer had discovered that very little literature existed in the United States on the subject of police work, so he located and read a number of European works on the subject, in particular, Criminal Psychology, by Hans Gross, an Austrian criminologist, and Memoirs of Vidocq, by Eugène François Vidocq, head of the detective division of the French police in Paris. He then set out on a program of modernization. He established a bicycle patrol and created the first centralized police records system, designed to streamline and organize criminal investigations. He established a call box network. And he trained his deputies in marksmanship.
In the ensuing years, Vollmer's reputation as the "father of modern law enforcement" grew. He was the first chief to require that police officers attain college degrees, and persuaded the University of California to teach criminal justice. In 1916, UC Berkeley established a criminal justice program, headed by Vollmer. At Berkeley, he taught O.W. Wilson, who went on to become a professor and continued efforts to professionalize policing, by being the first to establish the first police science degree at Municipal University of Wichita (now Wichita State University). This is often seen as the start of criminal justice as an academic field.
Vollmer was also the first police chief to create a motorized force, placing officers on motorcycles and in cars so that they could patrol a broader area with greater efficiency. Radios were included in patrol cars. He was also the first to use the lie detector, developed at the University of California, in police work. Vollmer supported programs to assist disadvantaged children, and was often criticized for his leniency towards petty offenders such as drunks and loiterers. He also encouraged the training and employment of female and African American police officers.
In 1921, Vollmer was elected president of the International Association of Chiefs of Police. Vollmer left the Berkeley Police Department for a brief stint as police chief of the Los Angeles Police Department from 1923 to 1924, but returned upon being disillusioned by the extent of corruption and hostility towards leadership coming from outside the department.
Vollmer married Millicent Gardner in 1924. They had no children. In 1926, Vollmer played himself in the silent serial Officer 444 which was filmed in Berkeley under the direction of John Ford's brother Francis Ford.
Vollmer contributed to sections of the Wickersham Commission national criminal justice report of 1931, namely to the fourteenth and final volume, The Police, which advocated for a well-selected, well-educated, and well-funded professionalized police force. Other portions of the Wickersham report were sharply critical of current police practice; one of the volumes was entitled Lawlessness in Law Enforcement.
He retired from the Berkeley Police in 1932 as his eyesight began to fail. He was then appointed as a professor of police administration in the Political Science Department at the University of California, and went on to found its School of Criminology. He was also among the five people elected as the first directors of the East Bay Regional Parks District in 1934. The same year Vollmer was awarded the Public Welfare Medal from the National Academy of Sciences.
Vollmer became afflicted with Parkinson's Disease late in life, and also cancer. He refused to be bed-ridden, and chose to end his own life at age 79 in 1955.
Vollmer was against police involvement with the problem of drug addiction. Vollmer wrote that enforcement of moralistic vice laws leads to police corruption and "engenders disrespect both for law and for the agents of law enforcement." Vollmer supported the establishment of federal distribution, at cost, of habit forming drugs.Bald Peak in the Berkeley Hills was renamed Vollmer Peak.
In 2004 the Alameda County Sheriff's office christened a new 32-foot custom patrol boat the August Vollmer.
In 1959 the American Society of Criminology established the August Vollmer Award to recognize an individual whose scholarship or professional activities have made outstanding contributions to justice or to the treatment or prevention of criminal or delinquent behavior.