Stereotactic ablative body radiation therapy (SBRT) has emerged as the standard treatment for inoperable patients with stage I non-small cell lung cancer (NSCLC). In the current study, we retrospectively analyzed a medically operable patient cohort with stage I NSCLC who refused surgery and subsequently underwent SBRT. Overall survival (OS) and progression-free survival (PFS) were calculated. Between April 2014 and July 2020, 55 patients were enrolled to the study. Forty (72.7%) patients were male, with a mean age of 69.85 ± 4.65 years (range 59–78 years). ECOG performance status were 0 and 1, except for one case. At the time of analysis, 8 deaths were observed. Of these, 25% (n = 2) died due to cardiac events, 12.5% (n = 1) due to pulmonary causes, 12.5% (n = 1) due to lung cancer-related causes, and the cause of death was unknown for 50% (n = 4). The pulmonary causes and cardiac events were not associated with radiation-induced toxicity. The median survival time was 34 months, with a range of 12 to 44 months. 2-year OS and PFS were 97% and 98%, 3-year OS and PFS were 82% and 77%, respectively. Treatment with SBRT was well tolerated and no grade 3 and 4 treatment-related adverse events were observed. SBRT seems to be a well- tolerated and effective alternative for patients with operable early-stage NSCLC.