Background/Objectives: Root canal treatment (RCT) is a crucial procedure for preserving dental health. While its clinical success rates are well documented, patient-reported outcomes regarding quality of life remain less explored. This study aimed to assess the long-term impact of RCT performed in an educational hospital on patients’ oral-health-related quality of life (OHRQoL) using the Oral Health Impact Profile-14 (OHIP-14). Methods: A total of 1500 patients who underwent non-surgical RCT between April 2018 and February 2023 were called and invited for a follow-up visit. During the visit, all teeth that had undergone RCT were assessed clinically and radiographically by two calibrated examiners to evaluate RCT quality and pre- and post-treatment periapical index (PAI) scores. Demographic information and OHIP-14 responses were collected, and the data were recorded. Results: Patients reported high levels of satisfaction (95%) and no negative impact on their OHRQoL. Statistical analysis revealed that post-operative periapical index (PAI) scores (p < 0.001), patient gender (p = 0.003) and nationality (p = 0.029) significantly influenced OHRQoL perceptions; Conclusion: These findings emphasize the effectiveness of RCT in enhancing patients’ quality of life and highlight the impact of demographic factors—such as gender and whether the patient is a resident or a national of the country, along with post-treatment severity of the disease—on patient-reported outcomes.