Billie was born in Oakland, California and raised in Rodeo, California. He is the youngest of six children to Andrew "Andy" Marsicano Armstrong and Ollie Jackson. His father worked as a jazz musician and truck driver to support his family. He died of esophageal cancer on Septemebr 10, 1982. The song "Wake Me Up When September Ends" is a memorial to his father. He has five older siblings: David, Alan, Marci, Hollie and Anna. His mother worked at Rod's Hickory Pit restaurant in El Cerrito, where Armstrong and Dirnt played their first gig in 1987.
Along with Hillcrest Elementary, Armstrong attended Carquinez Middle School and John Swett High School, both in Crockett, and later transferred to Pinole Valley High School in Pinole. On his 18th birthday (February 17, 1990), he dropped out to pursue his musical career.
In 1986, age 15, Armstrong formed a band called Sweet Children with his childhood friend Mike Dirnt. In the beginning, Dirnt and Armstrong both played guitar, with John Kiffmeyer, also known as Al Sobrante, on drums, and Sean Hughes on bass. After a few performances, Hughes left the band in 1988; Dirnt then began playing bass and they became a three-piece band. They changed their name to Green Day in April 1989, choosing the name because of their fondness for marijuana. That same year, they released their debut EP 1,000 Hours through Lookout! Records. They recorded their debut studio album 39/Smooth and the extended play Slappyin 1990, which were later combined with 1,000 Hours into the compilation 1,039/Smoothed Out Slappy Hoursin 1991. Tré Cool eventually became Green Day's drummer in late 1990 when Sobrante left Green Day in order to go to college. California punk band Rancid's lead singer Tim Armstrong asked Armstrong to join his band, but he refused owing to the progress with Green Day. Cool made his debut on Green Day's second album, Kerplunk. With their next album, Dookie (1994), the band broke through into the mainstream, and have remained one of the most popular rock bands of the 1990s and 2000s with over 60 million records sold worldwide.
In 1990, Armstrong met Adrienne Nesser at one of Green Day's early performances in Minneapolis, Minnesota. They married on July 2, 1994; the day after their wedding, Adrienne discovered she was pregnant. Armstrong's son, Joseph Marciano Armstrong, who was born February 28, 1995, plays drums in a Berkeley-based band named SWMRS. In a February 2014 interview with Rolling Stone Armstrong described how his sudden marriage and having a son was "mental" saying, "I was very impulsive at that time. I think that impulsive behavior was meant to counteract the chaos in my life."
Billie Joe's second son Jakob Danger is a guitarist and singer/songwriter who released his first material online in 2015 featuring drums and bass by SWMRS band members Joseph Armstrong and Sebastian Mueller and produced by Billie Joe. Currently, he is the guitarist/lead vocalist for the band Mt. Eddy, alongside Kevin Judd and brothers Chris and Enzo Malaspina.