Since 1921, it has provided legal assistance to indigent individuals charged with violations of California state law by the San Francisco District Attorney's Office.

In 1974, Robert Nicco was appointed Public Defender and subsequently elected, after having served as Chief Attorney under Mancuso.

Jeff Adachi was elected San Francisco Public Defender in November 2002 and held office from January 2003 until his death in February 2019.

Raju is the only elected public defender in California and runs an office of more than 100 attorneys and 60 staff members, which has a $24 million budget and serves 23,000 clients each year.

In March 2011, Adachi released surveillance tape gathered by public defender investigators showing plainclothes narcotics officers from the San Francisco Police Department entering rooms in the Henry Hotel and conducting warrantless searches of rooms and people, taking property from residents, and roughing up citizens.

[10][11] Adachi further revealed evidence that owners of single resident occupancy hotels had been bullied by police into handing over master keys to tenant rooms.

[13] In 1999, the San Francisco Public Defender's office launched a Clean Slate program to expunge the criminal records of people whose old convictions had become obstacles to obtaining work, housing, and educational opportunities.

[20] In October, 2017, the office launched its Pretrial Release Unit, which aims to reduce wealth disparities in pre-arraignment representation and unnecessary pre-trial incarceration by providing legal advice and advocacy to indigent arrestees.

[21] The program likewise aims to reduce the county jail population by increasing arrestees’ likelihood of pretrial release A study from the California Policy Lab at University of California Berkeley found that the program saved $806,508 in taxpayer money and thousands of jail beds during its first five months of operation.