Robert Trujillo was born in Santa Monica, California, on October 23, 1964. He is of Mexican and Native American descent. He grew up in Culver City, California, where his father was a teacher at Culver City High School.[citation needed] Trujillo gained an interest in music during his childhood; his mother was a huge fan of soul music, particularly musicians like Marvin Gaye, James Brown, and Sly and the Family Stone.
Trujillo stated that "Jaco [Pastorius] was my hero growing up", and that the iconic jazz bassist changed his view of what the instrument could play: "Hearing him was like hearing Eddie Van Halen doing "Eruption" for the first time: You thought, 'What instrument is that?' I loved jazz fusion and branched out from there. But Jaco had an edge that far exceeded his jazz persona. He was funk, he was rock, he was soul. And his whole attitude was punk." He began playing in "a lot of backyard party bands", playing music by Black Sabbath, Ozzy Osbourne, Rush, and Led Zeppelin. He went to jazz school when he was 19 with the intention of becoming a studio musician, but he maintained his passion for rock and metal.[