Being the son of a famous surfer in the islands, Jeff Johnson, Jack Johnson naturally had an interest in surfing with his best friend Merik Richardson. He began with surfing at the age of 5, and by the time he was 17 he made the finals at the Pipe trial and became the youngest invitee ever to do so. Johnson suffered a surfing accident when he was 17. While recovering from the accident, he acquired an interest in music. Johnson began writing songs during his college years at the University of California, Santa Barbara, having played the guitar since 14.

He was brought up with influences such as Nick Drake, Cat Stevens, Ben Harper, the Beatles, Jimmy Buffett, Bob Marley Neil Young, Bob Dylan, Sublime, and A Tribe Called Quest. One day G. Love was introduced to Jack for a day of surfing and ended up recording Jack’s song “Rodeo Clowns” for his last album Philadelphonic. It became the first single from the album and Jack sang and played on the track. His four-track demo caught the ears of Ben Harper's producer and right-hand man, J. P. Plunier, who worked with Jack on his debut album Brushfire Fairytales in early 2001 with Harper and his lap steel guitar making a guest appearance. He has two sons, one being named Michael Johnson.

Jack Johnson learned how to surf and skate from his father's best friend Alex Conell. Johnson learned to play the guitar at age of fourteen. He was a professional surfer until an accident at Pipeline in which his front teeth were knocked out and he received more than 150 stitches. Although that is when most people believe he changed from a surfer to an artist, in a recent Rolling Stone cover story (March 6, 2008) he stated that it actually happened a week before in the finals of the trials of the Pipeline Masters on Oahu.

At the age of 17 he became the youngest competitor to ever reach the finals. Jack was eventually disqualified after failing to catch three waves. Jack realized that the competitiveness was too much for him, "guys were ready to kill each other to catch the next wave," Johnson remembers. The accident allowed time for Jack to start on his new passions, the guitar and making music. He stated about the accident, "I like to joke that I hit my head so hard that that's why I'm so mellow, but I think it did mellow me out." While he was recovering in bed, he spent his time writing songs and playing guitar. However, Johnson didn't seriously pursue a career in the arts until his college years at the University of California, Santa Barbara. While in school, he met his wife Kim, for whom the song Do You Remember is written. Johnson also played rhythm guitar for the party band "Soil," and graduated with a degree in film.