After irrigation in intensive vegetable cultivation, the soil is filled with water leading to reduced oxygen content of the soil air which will affect vegetable growth and soil N2O emission. In this study, the effect of aerated irrigation and residue biochar on soil N2O emission, yield, and ion uptake of komatsuna grown in Andosol was explored. The experiment included four treatments; control (tap water irrigation), aerated water irrigation, pruning residue biochar with tap water irrigation, and a combination of aerated irrigation and biochar. The results showed that aerated irrigation had no effect on plant growth, but it also increased N2O emission by 12.3% for several days after planting. Plant ion uptake was not affected by aerated irrigation. Biochar amendment increased shoot dry weight and significantly reduced soil N2O emission by 27.9% compared with the control. Plant uptake of N and K also increased with biochar. This study showed that pruning residue biochar has the potential to mitigate N2O emission while increasing vegetable growth and plant nutrient uptake. However, the study soil, Andosol, already has high soil porosity with low bulk density. Thus, further injection of air through irrigation showed no effect on plant growth but increased N2O emission, hence soil aeration was not a limiting factor in Andosol.