For a study, researchers sought to look into the relationship between infertility-related stress and QoL in infertile women with PCOS and see if body mass index (BMI) influenced this relationship. Given its association with increased susceptibility to stress, obesity may confer an increased adverse effect of infertility-related stress. A cross-sectional study was carried out with 306 participants recruited from an infertility outpatient clinic. This study used a self-administered, structured questionnaire that included the COMPI Fertility Problem Stress Scale (COMPI-FPSS) and the modified PCOS health-related QoL questionnaire (MPCOSQ). The PROCESS macro in SPSS was used to run the moderation model. The mean QoL score was 142.67 (SD=20.11), with scores ranging from 93 to 183 (theoretical range = 30–210). QoL was negatively related to infertility-related stress (r=−0.373, P<0.001). The interaction term between infertility-related stress and BMI significantly predicted QoL (β=−0.154, P=0.005, f2=0.03) and emotional disturbance (β=−0.170, P=0.002, f2=0.04), according to moderation analysis. Higher BMI, in particular, exacerbated the effect of infertility-related stress on QoL and emotional disturbance. As a result, infertile women with PCOS had poor quality of life. The role of BMI in moderating the relationship between infertility-related stress and QoL provided a better understanding of individual differences. Interventions to improve QoL in infertile women with PCOS should reduce infertility-related stress, particularly in women with a high BMI.