Purpose Postoperative complications have a significant impact on perioperative outcomes; however, their association with the long-term prognosis remains unclear. We evaluated the impact of postoperative complications on the long-term outcomes after curative surgery in lung cancer patients. Methods This study included 1129 patients with primary lung cancer who underwent lobectomy between April 2011 and March 2017. Univariate and multivariate analyses were performed to assess the association of postoperative complications with the overall and recurrence-free survival. Results Postoperative complications were observed in 147 (13.0%) patients over a median follow-up period of 5-years. Compared to patients without complications, those with complications showed had worse long-term outcomes, including the 5-year overall survival (75.3% vs. 86.1%, p  < 0.001) and 5-year recurrence-free survival (64.2% vs. 74.4%, p  = 0.004). A multivariate analysis revealed that the incidence of postoperative complications was significantly associated with the overall survival (hazard ratio = 1.665, p  = 0.006) and recurrence-free survival (hazard ratio = 1.416, p  = 0.025) in all patients. The prognostic influence was greater in patients with pathological stages II and III cancer (overall survival: hazard ratio = 2.019, p  = 0.005; recurrence-free survival: hazard ratio = 1.90, p  = 0.001) than in those with pathological stage I cancer. Conclusion Postoperative complications are independent predictors of the overall and recurrence-free survival in lung cancer patients, especially advanced-stage cancer patients.