Background: For better water resources management in the areas of water shortage for crop production, deficit irrigation is very important. The understanding of the yield response factor to water deficit is crucial for efficient irrigation water management. Deficit irrigation for studying yield response factors is always practiced in the way of stressing the demand of the crops. The present study was done for the determination of the seasonal yield response factor of red Bombay onion variety under Arba Minch agro climate condition. Furthermore, it also examined the effect of furrow irrigation systems on the seasonal yield response factor. Methods: The experiment was conducted from August to November 2019. The experiment had six treatments, which were the combination of two furrow irrigation systems and three irrigation levels. Data were collected for soil moisture before and after each irrigation and bulb yield. The seasonal yield response factors were determined through simple linear regressions using SPSS software. Result: When considering the furrow irrigation system as a factor, the seasonal yield response factor for alternate furrow irrigation system was 1.18 while for paired row furrow irrigation system was 1.07. This red Bombay variety of onion clearly shows more sensitive to water stress for alternative furrow irrigation systems than paired row furrow irrigation systems. Therefore, in the area of water shortage paired row furrow irrigation system is better than alternate furrow irrigation system. The seasonal yield response factor as a wall for red Bombay onion variety in Arba Minch agro-ecological condition was 1.12. Therefore, the red Bombay onion variety in Arba Minch agroclimate condition was sensitive to water stress.