Objective To evaluate the evolution of voice quality in patients after type I-VI transoral CO2 laser cordectomy (TLC) by using validated voice outcome measures over a 12-month period. Study Design Prospective uncontrolled study. Setting Monocenter study. Methods Patients with laryngeal carcinoma who were eligible for type I-IV TLC were prospectively recruited from a tertiary medical center. The following outcomes were assessed throughout the 12-month posttreatment period: Voice Handicap Index (VHI), GRBAS (grade of dysphonia, roughness, breathiness, asthenia, strain), maximal phonation time, fundamental frequency (F0), F0 standard deviation, percentage jitter, percentage shimmer, noise-to-harmonic ratio, and speech fluency. Analyses were performed considering 2 groups of cordectomies: type I-III vs IV-VI. Results A total of 131 patients completed the evaluations, totaling 76 type I-III and 55 type IV-VI cordectomies. In type IV-VI, breathiness and maximal phonation time significantly worsened from pretreatment to 1 month posttreatment ( P < .05). In the type I-III cordectomy group, VHI, shimmer, roughness, breathiness, and strain significantly improved from pretreatment to 3 months posttreatment, while VHI, F0 standard deviation, shimmer, jitter, grade of dysphonia, roughness, breathiness, and strain improved from baseline to 6 months. Assessments at 12 months posttreatment revealed significant improvements for VHI, shimmer, jitter, noise-to-harmonic ratio, grade of dysphonia, roughness, breathiness, and strain. In the type IV-VI group, VHI significantly improved from baseline to 3, 6, and 12 months posttreatment. Strain improved at 6 and 12 months while roughness improved from baseline to 12 months. Maximal phonation time significantly worsened over the 12-month evaluation period. Conclusion The effect of TLC on voice quality depends on its type. VHI was identified as the most indicative tool of voice changes irrespective of TLC type.