Kiedis was born in Grand Rapids, Michigan, to Margaret "Peggy" Nobel and struggling actor John Michael Kiedis, known professionally as Blackie Dammett.
In 1966, when Kiedis was three years old, his parents divorced, and he was raised by his mother in Grand Rapids. His mother later remarried and had two more children. Each summer, Kiedis would visit his father in Hollywood for two weeks,
a time during which the two would bond. He idolized his father and recalled: "Those trips to California were the happiest, most carefree, the-world-is-a-beautiful-oyster times I'd ever experienced." In 1974, when Kiedis was 12, he moved to Hollywood to live with his father full-time
Kiedis, Slovak, and Flea began to create their own music after finding inspiration in a punk-funk fusion band called Defunkt.
Kiedis rejected the violence and misogyny associated with the Los Angeles punk rock scene at the time, and wished to create a more peaceful environment that would encourage women to come to concerts.
The three reunited with Irons, who had recently left his previous band Anthym, to form a new band called Tony Flow and the Miraculously Majestic Masters of Mayhem. The band had only one song, titled "Out in L.A.", and was formed for the purpose of playing the song once.
Kiedis's father, Blackie Dammett, was an actor who appeared in over 50 movies and television shows. Dammett also ran the band's fanclub for many years. Dammett's autobiography, Lords of the Sunset Strip, was released on March 31, 2013.
Through Dammett, Kiedis also has a much younger half-brother. During the Chili Peppers show of June 25, 2017, in Grand Rapids, Kiedis dedicated "Soul to Squeeze" to his father, who was suffering from dementia. Dammett died on May 12, 2021
Kiedis has battled drug addiction, including heroin and cocaine, throughout his life. Since his father used drugs regularly, Kiedis was constantly exposed to drug-using and drug-dealing behavior while growing up.
Some of Kiedis's early drug use came from substances he got from his father, including marijuana, which he first smoked when he was 12 years old.
Kiedis tried to get clean after Red Hot Chili Peppers guitarist Hillel Slovak died of a heroin overdose on June 25, 1988, saying he would never shoot up again. He entered rehab and ended up staying clean for five years,
but he relapsed in 1994, causing a major delay in the release of the band's 1995 album, One Hot Minute. Kiedis kept using on and off over the next six years
In 1990 Kiedis received a conviction for indecent exposure and sexual battery in Virginia related to an incident at George Mason University in Fairfax County in April 1989.
He was ordered to pay a fine on both counts. Kiedis was accused of touching a woman's face with his penis after a concert at George Mason University in Fairfax County on April 21, 1989