Smallholder farmers of are involved in onion production in very small amount. Even if the onion production techniques generate very high income, productivity is being threatened because of limited introduction of improved onion varieties. Therefore, this study was conducted to evaluate yield performance of improved onion varieties under supplementary irrigation. The treatments consisted of five varieties namely, Adama red (standard check), Bombay red, Nasik red, Nafis and Robaf using a randomized complete block design with three replications. Results of combined data analysis revealed that the highest fresh bulb weight of 126.4 g and 121.8 g was observed in the Bombay red and Nafis varieties respectively, which differed significantly from standard check. Similarly, the highest bulb diameter was observed from variety Nafis (20.4 cm. The highest marketable yield per plot was obtained from variety Bombay red (10.8 kg) which was not significantly differed from other varieties. On the other hand, the highest total yield (12.13 t/ha) was obtained from variety Bombay red; which however, was statistically at par with variety Nafis with the total yield of 11.68 t/ha. From the results, Bombay red had better yield performance with the lowest unmarketable yield. Therefore, variety Bombay red can be used for better production in the study area and similar agroecologies.