Background: The impact of delayed surgery on clinical outcomes after histologic or radiologic diagnosis of clinical stage I adenocarcinoma remains controversial. We evaluated the effects of delayed surgery on outcomes of patients with early-stage lung cancer. Methods: Associations between time intervals of “histologic diagnosis-to-surgery” (HDS), “radiologic diagnosis-to-surgery” (RDS), and overall survival in clinical stage I adenocarcinoma were assessed using multivariable Cox proportional hazard analysis. Results: A total of 561 consecutive patients with preoperative histologic confirmation of stage I lung cancer between 2006 and 2016 were included. Median time to HDS and RDS were 20 (2–267) and 58 (38–2,983) days. Higher Charlson comorbidity score, receiving brain magnetic resonance imaging screening, and video-assisted thoracoscopic surgery approach were significantly associated with increased risk of late HDS (>21 days). Smaller tumor size and non-radiologic solid-dominant pattern were significantly associated with increased risk of late RDS (>60 days). In the overall cohort, worse 5-year overall survival was associated with late HDS compared to early HDS (75.9% vs. 85.5%, P=0.003). No significant differences were found in later late vs. early RDS (83.7% vs. 83.3%, P=0.570). In 286 propensity-score matched patients, late HDS [adjusted hazard ratio (aHR) =2.031, P=0.038], higher Charlson comorbidity score (aHR=1.610, P=0.023), larger tumor size (aHR=2.164, P=0.031), without brain magnetic resonance imaging screening (aHR=2.051, P=0.045), and tumor with angiolymphatic invasion (aHR=4.638, P=0.001) were significantly associated with lower overall survival. Conclusions: In patients with stage I lung adenocarcinoma, delayed surgery after a histologic diagnosis is an independent predictor of overall survival after adjusting for clinical risk factors, suggesting meaningful differences in clinical outcomes between timely vs. delayed surgeries.