Justin Sanchez was born and raised in the Bronx. He served as a constituent service liaison for a local council member, and as the community board liaison for the office of Bronx Borough President Ruben Diaz Jr, where he was promoted to the director of external affairs. He then served as chief of staff to New York State Senator Nathalia Fernandez. He has also served as the director of Latino Outreach for the New York State Democratic Party, vice president of the Bronx Young Democrats, chair of the Hispanic and Latino Caucus of the Young Democrats of America, and president of the Stonewall Democratic Club.