Surgical resection is recommended for operable stage I non-small-cell lung cancer (NSCLC), while radiotherapy reserved for inoperable patients. Very comorbid patients may receive no treatment at all. Social determinants of health (SDOHs) may influence access to these treatments. We examined how SDOHs affect treatment modality among these patients using a population-based retrospective cohort study using ICES data including adults with stage I NSCLC diagnosed between 2007 and 2023. Multivariable logistic regression assessed associations between SDOH and treatment received. Of 19,179 patients, 54.4% received only surgery, 15.8% received only radiotherapy, 27.5% received no treatment, and 2.3% received surgery and radiotherapy. Surgery was less likely in patients aged >80 versus <50 (OR 0.07, p < 0.001), patients with frailty (OR 0.38, p < 0.001), patients with ≥5 comorbidities (OR 0.21, p < 0.001), or those who were not rostered with a family physician (OR 0.59, p < 0.001). Recent immigrants were more likely to undergo surgery (OR 1.23, p = 0.035), as well as those in the highest neighbourhood income quintile (OR 1.45, p < 0.001). Surgery was less likely for those living 50-100 km from a cancer centre (OR 0.85, p = 0.004). Radiotherapy was more likely in patients aged >80 (OR 9.86, p < 0.001), those with ≥5 comorbidities (OR 2.23, p < 0.001), or those in the lowest household income quintile (OR 1.27, p = 0.009). Recent immigrants were less likely to receive radiotherapy (OR 0.69, p = 0.005). SDOHs independently influence treatment type for stage I NSCLC.