The law requires all new semi-automatic handguns to come equipped with a device that stamps each bullet with the gun's make, model, and serial number.
The law will not be applied to any of the 1,200 guns already on the state's firearm roster.
The law has angered gun rights advocates including the Calguns Foundation which challenged requirements of the state's handgun roster as unconstitutional in a federal court filing.
The law couldn't take effect as it was supposed to in 2010 because of patents on the technology, including at least one filed by the Calguns Foundation to delay the law's implementation.
On Friday, Attorney General Kamala Harris officially certified and announced that patents were no longer an issue. Former state Assemblyman Mike Feuer, who authored the law, hailed it as a "monumental day for law enforcement."
"This very important technology will help us as law enforcement in identifying and locating people who improperly and illegally use and discharge firearms," said Harris.
Reports show about 40 percent of California's homicides are unsolved, most of which usually involve firearms.
The Associated Press contributed to this report.