INTRODUCTION: Methodological heterogeneity and reporting bias complicate interpreting endodontic outcomes. Supported by the American Association of Endodontists and its Foundation, this study developed the Core Outcome Set in Endodontics (COS-ENDO) to standardize reporting for studies of Nonsurgical Root Canal Treatment/Retreatment, Surgical Endodontics, Vital Pulp Therapy, Apexification, and Regenerative Endodontics. This article, the last in a 5-part series, focuses on COS-ENDO for Apexification and Regenerative Endodontics, while other parts address the remaining treatments. METHODS: Outcomes were identified through scoping reviews and a web-based survey of American Association of Endodontists practicing members. In a 2-round Delphi survey, clinicians, patients, and researchers rated outcomes on a 9-point scale. Ratings were assessed against consensus criteria, and a virtual meeting finalized COS-ENDO. RESULTS: Of the 97 invited participants to Round 1, 77 registered, and 73 (24 Academicians/Researchers, 26 Clinicians, and 23 Patients or their parents/caregivers) assessed 51 outcomes, with 18 excluded. The remaining outcomes-7 achieving consensus for inclusion and 26 lacking consensus-advanced to Round 2 for re-rating by 70 participants. This resulted in 14 outcome achieving consensus for inclusion, and 19 lacking consensus. In the final meeting, 16 participants finalized the COS-ENDO for Apexification and Regenerative Endodontics, including Tooth survival, Pain, Signs of infection, Radiographic evidence of periradicular healing, Continued root development, Success, Functional tooth, Need for further intervention, and Adverse events/Complications. CONCLUSION: COS-ENDO is an important step in standardizing outcome reporting in endodontics, ensuring consistent reporting and enhancing research utility. Further efforts are needed to establish optimal measurement methods.