His research investigates the transnational and social history of Southeast Asia after the Second World War. Loh is author or editor of six books, including Squatters into Citizens: The 1961 Bukit Ho Swee Fire and the Making of Modern Singapore (2013), The University Socialist Club and the Contest for Malaya: Tangled Strands of Modernity (coauthored, 2012), and Making and Unmaking the Asylum: Leprosy and Modernity in Singapore and Malaysia (2009).