This study quantified the effects of paddy straw mulching and irrigation regimes on yield, water use, and productivity of spring maize during 2019 and 2020. An experiment was conducted with treatment combination of three paddy straw mulch levels (no mulch, 6 t ha-1, and 9 t ha-1) and five irrigation regimes {four regimes based on depletion from available soil moisture (DASM) at 20, 30, 40, and 50% DASM; and recommended farmers practice {based on irrigation water:cumulative pan evaporation (IW:CPE) = 1.05} in randomized complete block design. The results revealed that straw mulching improved soil moisture storage, crop growth, and productivity. Mean grain yield increased by 13 and 15% with straw mulching at 6 and 9 t ha-1 compared to no mulch, respectively. Crop irrigated at 20% DASM resulted in 4.9 and 5.3% higher grain yield in comparison with the current recommended practice in 2019 and 2020, respectively. Furthermore, straw mulch either 6 or 9 t ha-1 and irrigated at 30% DASM yielded statistically similar to that raised without mulch and irrigation at 20% DASM. Therefore, straw mulching at 6 and 9 t ha-1 and irrigation at 30% DASM saved 120 and 240 mm irrigation water compared with crop raised without mulch and irrigated at 20% DASM during 2019 and 2020, respectively. From a water-saving perspective, straw mulching at 9 t ha-1 and irrigation at 30% DASM appear as the most effective practice to enhance grain yield and water productivity of spring maize.