Understanding variety × environment interaction (VEI) and variety × management interaction (VMI) are critical for deploying superior crop varieties to responsive environments. We evaluated 15 common bean (Phaseolus vulgaris L.) varieties in a split-plot design under two fertilizer regimes, for two seasons, and in six locations in Rakai and Hoima districts, Uganda. We assessed VEI and VMI effects on plant vigor, plant height, number of pods per plant, grain yield, and reaction to angular leaf spot (ALS) (Psuedocercospra griseola), common bean rust (CBR), common bacterial blight (CBB) (Xanthomonas campestris pv. phaseoli), and anthracnose on pods (ANTP) (Colletotrichum linemuthianum) under field conditions. The seasons and fertilizer levels were considered as separate environments resulting in 24 environments. Variety × location × season interaction had a significant effect on the reaction to ALS, CBR, and grain yield. The VEI and VMI analysis grouped the 12 environments into two mega-environments based on grain yield in different seasons and fertilizer levels. ROBA1, Masindi Yellow Long, and NABE2 varieties had the highest grain yield in the different mega-environments. The Farmers’ variety and varieties KATX69 and KATX56 were stable, whereas NABE2, RWR719, and ROBA1 were unstable in grain yield performance. Genotypic correlations between traits were stronger in Hoima than in Rakai. The diseases correlated negatively with grain yield, and were strong in the second season of Hoima district. The Katumani varieties and landraces were susceptible to disease in the environments. Thus, increased production of landraces, KATX69 and KATX56 could be attained by improving their disease resistance.