To examine the joint influences of physical activity (PA) and family history (FH) of diabetes on subsequent type 2 diabetes (T2D), the authors pooled and analyzed data from 2 community-based urban adult prospective cohort studies in 2011 in Nanjing, China. Among 4550 urban participants, the 3-year cumulative incidence of T2D was 5.1%. After adjustment for potential confounders, compared with those with FH+ and insufficient PA, the adjusted odds ratio (95% confidence interval) of developing T2D was 0.42 (0.18, 0.98) for participants with sufficient PA and FH+, 0.32 (0.22, 0.46) for participants with insufficient PA and FH–, and 0.15 (0.08, 0.28) for participants with sufficient PA and FH–. Such significant graduated associations between PA/FH and risk of developing T2D were also identified in either men or women, separately. Sufficient PA and FH– may jointly reduce the risk of developing T2D in urban Chinese adults.