Aim: To develop an evidence-based framework of nurse preceptor competency domains and competency descriptors for use in nurse preceptor professional development. Background: Nurse preceptors are registered nurses who coach, support and assess nursing students while simultaneously caring for patients. Working as both clinician and educator requires preceptors to develop additional skills. However, preceptor preparation is often overlooked and may not be evidence based. Design: A modified e-Delphi study. Methods: A three-phase e-Delphi method informed the study that was conducted between March and September 2023. In the first preparatory phase an expert group distilled the results of a previous literature review identifying seven preceptor competency domains and more than 200 competency descriptors. Two e-Delphi rounds followed. A 70% rater agreement response threshold was chosen as appropriate in this study. The CREDES reporting framework was followed. Results: In the preparatory phase, the expert group (n=6) reached consensus on six preceptor domains and 57 preceptor descriptors. In Round 1, nurse preceptors (n= 89) rated the domains and descriptors using a four-point Likert scale; from not important to very important. Six domains and 34 competency descriptors were ranked as very important’. Round 2 participants (n=30) who opted in from Round 1 indicated their 100% agreement with the Round 1 results. The results reveal that preceptors resonate intuitively with the six domains Role model, Facilitator, Leader, Evaluator, Teacher and Coach and the related descriptors. Conclusion: The preceptor evidence-based competency framework offers registered nurse preceptors and their employers the opportunity to focus efforts in developing a nurse preceptor workforce. The framework can be used to design preceptor professional development and offers registered nurses a self-assessment tool to identify their preceptorship skills strengths and areas for development. If implemented in these ways the framework may benefit healthcare organisations to provide quality nurse preceptorship, thus enhancing the clinical learning experiences of nursing preceptees.