Background: Despite the introduction of the National Health Insurance Scheme (NHIS) in 2019 to improve healthcare financing and services, the healthcare system in Zambia still faces challenges that negatively affect patient satisfaction. Aim: Assess and investigate the factors influencing patient satisfaction with NHIS-provided services at a third-level tertiary public hospital. Setting: The study was conducted at the OPD of Levy Mwanawasa University Teaching Hospital (LMUTH) in Lusaka, Zambia. LMUTH was purposefully chosen because it was one of the first NHIS-accredited facilities and because of its importance as the second-largest publicly financed tertiary referral hospital. Method: This was a mixed method cross-sectional survey and data were collected from a systematically chosen sample of 270 respondents using an interviewer-administered modified SERVUAL 5-point Likert scale questionnaire in May 2024. The data were analyzed using descriptive and inferential analysis. Results: 83 percent were satisfied with the NHIS-provided services. Education level, duration of NHIS enrollment, communication from NHIMA, drug availability, staff attitude, and waiting time were identified as significant factors. However, key predictors identified were employment status (OR = 0.237, p = 0.030), and communication and feedback from NHIMA (OR = 2.922, p = 0.001). Conclusion: Findings show a high NHIS satisfaction level identifying significant factors and key predictors. Future research should explore the long-term effects and satisfaction levels across various demographic groups and regions. Contribution: This study suggests improved NHIS communication, staff training, patient education, reduced waiting times, fostering courteous patient/staff interactions and enhancing diagnostic and pharmacy services.