Chronic rhinosinusitis (CRS) and asthma, when comorbid, may influence each other's disease course and decrease quality of life (QOL). Our objective was to determine if poorer asthma control due to CRS symptoms could be a mechanism for decreased QOL in asthmatic CRS patients.A total of 120 asthmatic CRS patients were recruited. CRS symptom burden was measured using the 22-item Sinonasal Outcome Test (SNOT-22) and patient-reported CRS symptom control, general health-related QOL was measured using the visual analog scale of the 5-dimensional EuroQol quality of life survey (EQ-5D VAS), and asthma control was measured using the Asthma Control Test (ACT). Association was sought between these outcome measures. A mediation model was created and validated to show that asthma control mediated the association between CRS symptom burden and decreased general health-related QOL.ACT score was associated with SNOT-22, EQ-5D VAS was associated with SNOT-22 score, and EQ-5D VAS was associated with ACT score. A statistically significant mediation effect for ACT score in the association between SNOT-22 and EQ-5D VAS), which represented 22.1% of the total effect of SNOT-22 on EQ-5D VAS, was identified. Similar findings were made for patientreported CRS symptom control instead of SNOT-22 score.In asthmatic CRS patients, a sizeable portion of CRS impact on QOL is indirectly mediated through the effect of CRS on poorer asthma control which may then drive decreased QOL.