Karl Castro helps cultivate conversations and interventions across various creative fields, with a focus on art, design, and cinema. His areas of interest include culture, books, travel, craft, history, and Filipino identity. He has designed, curated, and participated in exhibitions on institutional memory, contemporary issues, and community-based creative work. He creates art in various media and processes, including painting, weaving, collage, photomedia, and exhibition-making. He is an acclaimed book designer for cultural and scholarly volumes, and poster designer for diverse works of Philippine cinema. Castro has presented solo exhibitions at Chidori Bunka, Jorge B. Vargas Museum, Ayala Museum, Giant Dwarf Art Space, and Project Space Pilipinas. He has also created exhibitions and public installations with cultural institutions, libraries, and archives. In 2023, he was named awardee of the AIR⊿ Vol. 7 Osaka Artist-In-Residence program, where he explored the legacy of the first World Exposition in Asia and how the Philippines crafted its participation therein.