Gisondo was born in Palm Beach County, Florida. His parents, Stacey and Ron, are ocean engineers. His last name comes from his paternal grandfather, who was Italian-American. His other three grandparents were Jewish. After he began working frequently, he was homeschooled for several years. He attended Milken Community High School in Los Angeles, graduating in 2014. In 2015, he began attending the University of Southern California's film school, first full-time and then part-time before taking a hiatus to work full time. He has stated that he plans to finish his college education.