Background. In recent years, the healthcare landscape has seen a paradigm shift towards patient-centeredness in the provision of nursing care. The Primary Nursing Care Model has aroused interest as an approach that prioritizes the individualization and continuity of care, as well as the involvement of the patient in decision-making about their health, which may impact professional satisfaction, as well as the quality and safety of nursing care. Aim. This study aimed to evaluate the effectiveness of implementing the Primary Nursing Care Model in a hospital service. Methods. This study employed a quasi-experimental, single-group design with pre- and postintervention evaluations. It involved a convenience sample of 48 nurses from an internal medicine department. Data collection took place between June and November 2023. The intervention consisted of the implementation of the Primary Nursing Care Model. A questionnaire was used to characterize the sociodemographics of the participants, followed by instruments that made it possible to assess missed care, professional nursing practice environments, safety culture, job satisfaction for nurses, and the perception of activities that contribute to the quality of care. Results. The implementation of the Primary Nursing Care Model showed positive results compared to preimplementation. There were statistically significant differences when applying the Wilcoxon test, p < 0.005, with a reduction in missed care, an enhancement of the professional nursing practice environment and safety culture in nursing practice, as well as nurses’ job satisfaction and enhanced perception of the activities that contribute to the quality of care. Conclusion. The implementation of the Primary Nursing Care Model in a hospital setting has demonstrated valuable contributions, underscoring its potential to improve the quality of nursing care and promote patient-centered care approaches. Further research is recommended to explore its application in diverse healthcare settings.