Lablab-bean (Lablab purpureus) is a potential forage crop for improving the productivity of livestock sector in salt-affected areas. Farmers usually do not have enough knowledge about the right varieties for their fields, which results in lower yields. In this study, genotypic variations in agronomic and physiological traits were analyzed in three L. purpureus genotypes (ILRI-6529T, ILRI-184T, Local) commonly grown in Ethiopia. The pot experiments were conducted under 5 soil salinity levels (0, 5, 10, 15, 20 dS m−1). In general, agronomic traits (such as germination percentage, mean germination time, plant population, chlorophyll content, shoot and root length and biomass yield) and quality attributes (ash contents, CP, NDF, invitro organic matter digestibility and metabolizable energy) of all genotypes were negatively affected by increasing salinity levels. The maximum delay in germination was noted in ILRI-6529T genotype followed by ILRI-184T genotype and the local cultivar. The shoot and root lengths and chlorophyll content (SPAD) were higher in ILRI-6529T genotype than other two genotypes under all salinity levels. However, crude protein and metabolizable energy was higher in ILRI-184T genotype under higher salinity levels. The results indicate that ILRI-6529T and ILRI-184T genotypes performed superior than the local cultivar in terms of agronomic and quality parameters at all salinity levels. Therefore, these genotypes can be used to increase forage production and livestock productivity in salt-affected lands in Ethiopia due to its large dependence on livestock sector.