Justin is a principal at Mandelbaum Properties, a family-owned real estate development, investment and property management firm. Separately, he is the founder and president of Mainframe Studios, a 501(c)(3) arts organization whose mission is to create permanent affordable workspace for artists of all disciplines.

Justin is a native of Des Moines and spent 10 years living in New York, Tokyo and Philadelphia before returning in 2024. He was a co-founder of Vespera Investments, a real estate development firm that focused on socially and environmentally conscious community developments in the Northeast, and held positions at real estate private equity funds of Starwood Capital Group and Goldman Sachs. He earned BS and BA degrees with concentrations in real estate and finance from the Wharton School at the University of Pennsylvania through the Huntsman Program in International Studies & Business.