King, 42, was shot two or three times from a distance by birdshot fired from a shotgun. He then bicycled about 1½ miles back to his home in neighboring Rialto and called police. King was hit in the face, arms, back and torso, police said.
Authorities said when they arrived at the home, King and others appeared drunk and were largely uncooperative in providing information about the shooting.
King was taken to a hospital. His condition on Thursday was not immediately known.
The shooting may have involved a domestic dispute, San Bernardino police Lieutenant Scott Paterson said.
King, who is black, was videotaped being beaten by white Los Angeles police officers after he was stopped for speeding in 1991. Four officers were acquitted of most criminal charges in 1992, triggering rioting in Los Angeles and neighboring cities that left 55 people dead and caused $1 billion in property damage.
King sued the city over the beating and obtained a $3.8 million settlement.
However, he continued to have run-ins with the law. In 2004, he was ordered to spend 120 days in jail and ordered into treatment after pleading guilty to driving under the influence of the drug PCP after he lost control of his SUV in 2003 and slammed into a power pole in Rialto.
Rialto and San Bernardino are about 55 miles east of Los Angeles.