The San Diego County District Attorney is the elected district attorney for San Diego County, California. The office is responsible for the prosecution of both felony and misdemeanor violations of California state law that occur within the jurisdiction of the county. Courts within their jurisdiction includes the San Diego Superior Court, the California Courts of Appeal for the Fourth District, and the Supreme Court of California. Federal law violations are prosecuted by the U.S. Attorney for the Southern District of California. The current district attorney is Summer Stephan, who replaced Bonnie Dumanis on an interim basis after the latter resigned in July 2017.

As in most of California, some misdemeanor crimes are prosecuted by local city attorneys. City attorneys share jurisdiction with the district attorney to prosecute misdemeanors and infractions that are committed within the city's jurisdiction. All other misdemeanor, felony, and infraction violations that occur within San Diego County are prosecuted by the district attorney. As of 2011 the district attorney's office employs 310 attorneys. The district attorney's office claims a 90+ percent conviction rate. The main office is located in downtown San Diego in the Hall of Justice, with three regional centers in El Cajon, Chula Vista, and Vista.

In the first 20 years of San Diego County there were 23 men that held the office of district attorney, the first being William C. Ferrell.

District Attorney	Took office	Left office	Party	Notes
William C. Ferrell	August 19, 1801	May, 1851
Thomas W. Sutherland	1851	1852
James W. Robinson	1852	1855
Joseph R. Gitchell	1856	1858
James Nichol	1858	1859
William C. Ferrell	1859	1859
Dr. David B. Hoffman	1859	1861
A. N. Ensworth	1862	1862		Acting
Dr. David B. Hoffman	1862	1864
Unknown	1865	1865
Benjamin Hayes	1866	1867
William T. McNealy	1870	1873		Youngest District Attorney ever elected at age 21
Norman H. Conklin	1877	1879
William M. Smith	1879	1882
W. J. Hunsaker	1882	1884
E. W. Hendricks	1885	1886
Martin L. Ward	1893	1894
William Darby	1895	1895
A. H. Sweet	1895	1898
T. L. Lewis	1899	11902
Cassius Carter	1903	1906
Lewis R. Kirby	1907	1909
H. S. Utley	1909	1914
S. M. Marsh	1915	1917
Lewis R. Kirby	1918	1922
Chester C. Kempley	1923	1926
Unknown	1927	1931
Thomas Whelan	1931	1938
James B. Abbey	1938	1941
Thomas Whelan	1941	1948
James D. Keller	1948	1971
Edwin L. Miller	1971	1995
Paul J. Pfingst	1995	2003
Bonnie Dumanis	2003	2017
Summer Stephan	2017	Present

The San Diego District Attorney currently maintains a law enforcement arm called Bureau of Investigation. It consists of eight divisions, which include 130 District Attorney Investigators who are sworn California peace officers pursuant to § 830.1(a) California Penal Code and other non sworn staff.

Amongst its law enforcement duties and responsibilities are assignments which may include pre-trial, gang, economic, insurance, fraud investigations; family protection, child abduction, sex crimes, stalking, and special operation investigations. Apart from this, San Diego DA Investigators may be assigned to regional local, state and federal task forces such as: computer and high tech crimes, narcotics, auto theft, identity theft, violent crimes, SAFE and fraud.

33°01′N 116°46′W / 33.02°N 116.77°W / 33.02; -116.77