BACKGROUND Both CO2 transoral laser microsurgery (CO2 TOLMS) and radiotherapy (RT) are standard of care in early glottic carcinoma. However, previous studies focus on voice outcomes rather than swallowing outcomes. This study aimed to compare the late post-treatment effects of CO2 TOLMS and RT treatment on swallowing function in T1 glottic carcinoma. METHODS Forty patients (20 CO2 TOLMS and 20 RT) with T1 glottic cancer between May 2015 and January 2019 were included. Certain types of foods triggering dysphagia, any difficulties in bolus control, need to clean the throat, the sensation of lumping in the throat, choking, cough and xerostomia were questioned. Also, functional oral intake scale (FOIS), functional outcome swallowing scale (FOSS), Eating Assessment Tool-10 test (EAT-10) and flexible fiberoptic endoscopic examination of swallowing (FEES) findings were assessed. RESULTS CO2 TOLMS patients performed significantly better than the RT group regarding penetration and aspiration with 10 and 20 mL water according to the Penetration and Aspiration Scale (P < .05). The mean EAT-10 Score was found 0 in the CO2 TOLMS group, and 3.20 ± 3.24 in the RT group (P < .05) (lower score indicates a better outcome). According to the Yale Pharyngeal Residue Severity Scale for vallecula, there was no statistically significant difference in vallecular residue between the groups (P > .05). A significantly lesser residue in piriform sinus was detected in the CO2 TOLMS group compared to the RT group with 5 mL and 10 mL water, 5 mL and 20 mL honey consistency food and yogurt according to Yale Pharyngeal Residue Severity Scale (P < .05). CONCLUSIONS It is suggested that in the long term, CO2 TOLMS is more advantageous regarding swallowing function in the treatment of T1 glottic cancer.