Proper irrigation management and the application of organic soil amendments are among the most important strategies for mitigating the adverse effects of water stress and improving the productivity of agricultural and horticultural crops. . This study investigated the interactive effects of irrigation management and sawdust amendment on the yield and yield components of tomato (Solanum lycopersicum L.) grown in sandy soil. The experiment was conducted as a factorial arrangement with four irrigation levels, corresponding to allowable soil water depletion levels of 20–80%, and five levels of sawdust incorporation into the soil, ranging from 0 to 20% (v/v), with four replications. The results showed that the interaction between irrigation management and sawdust application had a significant effect at the 1% probability level on tomato yield, fruit number, and plant fresh weight. Under the 20% allowable soil water depletion level, increasing the proportion of sawdust up to an optimum level significantly increased yield and fruit number. For example, compared with the control treatment without sawdust, the application of 10% sawdust increased yield and fruit number by 22% and 31%, respectively. However, further increases in the proportion of sawdust resulted in declining trends in both yield and fruit number, indicating that tomato response was highly dependent on the optimum rate of the soil amendment. Overall, the results demonstrated that sawdust application can alleviate part of the adverse effects of water stress, probably by improving soil water-holding capacity, reducing evaporation from the soil surface, and enhancing the physical conditions of the root environment.