OBJECTIVE: Prediabetes has been suggested to increase risk for death; however, the definitions of prediabetes that can predict death remain elusive. We prospectively investigated the association of multiple definitions of prediabetes with the risk of death from all causes, cardiovascular disease (CVD), and cancer in Japanese workers. RESEARCH DESIGN AND METHODS: The study included 62,785 workers who underwent a health checkup in 2010 or 2011 and were followed up for death from 2012 to March 2019. Prediabetes was defined according to fasting plasma glucose (FPG) or glycated hemoglobin (HbA) values or a combination of both using the American Diabetes Association (ADA) or World Health Organization (WHO)/International Expert Committee (IEC) criteria. The Cox proportional hazards regression model was used to investigate the associations. RESULTS: Over a 7-year follow-up, 229 deaths were documented. Compared with normoglycemia, prediabetes defined according to ADA criteria was associated with a higher risk of all-cause mortality (hazard ratio [HR] 1.53; 95% CI 1.12-2.09) and death due to cancer (HR 2.37; 95% CI 1.45-3.89) but not with death due to CVD. The results were materially unchanged when prediabetes was defined according to ADA FPG, ADA HbA, WHO FPG, or combined WHO/IEC criteria. Diabetes was associated with the risk of all-cause, CVD, and cancer deaths. CONCLUSIONS: In a cohort of Japanese workers, FPG- and HbA-defined prediabetes, according to ADA or WHO/IEC, were associated with a significantly increased risk of death from all causes and cancer but not CVD.