The Penal Code of California forms the basis for the application of most criminal law, criminal procedure, penal institutions, and the execution of sentences, among other things, in the American state of California. It was originally enacted in 1872 as one of the original four California Codes, and has been substantially amended and revised since then.

The Penal Code enacted by the California State Legislature in February 1872 was derived from a penal code proposed by the New York code commission in 1865 which is frequently called the Field Penal Code after the most prominent of the code commissioners, David Dudley Field II (who did draft the commission's other proposed codes). The actual drafter of the New York penal code was commissioner William Curtis Noyes, a former prosecutor. New York belatedly enacted the Field Penal Code in 1881.

Prior to the promulgation of the Model Penal Code in 1962, the Field Penal Code was by far the most broadly influential attempt at codification of criminal law, but was severely flawed in that it actually continued many muddled common law concepts (like malice aforethought) when the point of codification was to clean up the common law. About this, UC Berkeley law professor Sanford H. Kadish wrote in 1987: "None of the codes I have considered had a larger measure of influence. None deserved it less." Before the enactment of the Penal Code, California relied on common law definitions of crimes as well as the accumulated case law that went back to the British common law of post-colonial times.

Like most of California's codes, the Penal Code is divided into parts, with the Penal Code containing six, most of which contain titles, some of which are in turn subdivided into chapters, with individual sections comprising the smallest unit of content. Unlike sections of the United States Code, any particular provision of the Penal Code is usually referenced by its section number alone, especially when a police officer in the state refers to a particular criminal act over their radio. Most of this article deals exclusively with the substantive criminal law set out in Part 1.

The first two titles of Part 1, up to Section 33, are preliminary and provide definitions of legal terms rather than definitions of, or punishments for, any specific crimes. The next group of titles, through Section 88, deal with crimes against the state itself, such as treason. Title 7, ending with Section 186, covers the state court system and crimes that can be committed therein, such as perjury. Title 8 covers the subject of violent crimes, and extends through Section 249. Title 9 (Sections 250 through 368) deals with offenses against public morals and decency. Title 10 (Sections 369 through 402) is devoted to "crimes against public health and safety," while Title 11 (Sections 403–423) is reserved for "crimes against the public peace." The topic of Title 12 (Sections 424–440) is crimes against public revenue, and of Title 13 (Sections 441 through 593), crimes against property. Title 14 (Sections 594–625) bears the heading "Malicious Mischief," but in addition to vandalism (Section 594), it also includes such offenses as trespassing (in Section 602). Title 15 (Sections 625–653) deals with "Miscellaneous Crimes," Title 16 (Sections 654-678) is labeled "General Provisions," and the last title of Part 1, Title 17 (679 and 680) delineates the "Rights of Victims and Witnesses of Crime."

Part 2 of the Penal Code (Sections 681–1020) codifies the state's criminal procedure system.

Part 3 of the Penal Code (Sections 2000–10007) codifies statutes governing the state's corrections system. Part 3 includes provisions governing the operation of the county jails and state prisons, as well as the administration of the death penalty.

Part 4 of the Penal Code (Sections 11006–14315) codifies statutes governing criminal investigations, prison officer training, police officer training, crime control, crime prevention, and gun control.