Introduction: The association between asthma and sinonasal disease has been established for years. As sinonasal disease is one of the factors that exacerbates asthma, effective treatment of this disorder may also improve and stabilize the asthmatic condition. This study examines the outcome of endoscopic sinus surgery (ESS) on asthmatic patients with massive nasal polyposis.   Materials and Methods: Forty-five asthmatic patients were included in the study. All were operated on and analyzed in our department. A questionnaire (SNOT-20) investigating the subjective evaluation of asthma and sinonasal states was presented to the patients, while objective evaluations including nasal rhinoscopy, forced expiratory volume in 1 second (FEV1), and steroid use were conducted with 1–2 years of follow up.   Results: Quality of life (QoL) improved in 97.8% of patients, while clinical symptoms, emotional signs, and social signs improved in 97.7%, 84.4%, and 93.3%, respectively. Medication use for asthma showed a similar improvement, with approximately 80% of patients reducing and 75.6% of patients discontinuing steroid use. A total of 91.1% of patients showed improvement in post-operative FEV1.   Conclusion:  ESS achieved a beneficial effect on sinonasal and asthma symptomatology in patients with nasal polyps and asthma. QoL was also improved in these patients.