To explore factors that influence the impact of nurse practitioners' clinical autonomy with a self-determining perspective. Worldwide, there is a significant demand for healthcare professionals such as the nurse practitioner in meeting some healthcare needs across patients' lifespans. Factors influencing nurse practitioners clinical autonomy can impact the full utilisation of the role in practice. Limited evidence exists that describes or researches nurse practitioner clinical autonomy. Instead, there is a focus in the literature on strategic debates, role confusion and nurse practitioners reporting the straddling between nursing, allied heath professionals and medicine in the provision of healthcare services. A cross-sectional study design was used in a purposive sample in a national sample of nurse practitioners in Ireland across a full range of healthcare settings. Additionally, the survey included open comments sections to capture qualitative comments by the nurse practitioners themselves. Self-determination theory is rooted in an organismic dialectical stance. This study used a convenience sample of n = 148 from a total sample of n = 448 (33%) of the population. The Dempster Practice Behavioural Scale and an initially validated advanced nursing practice clinical autonomy scale were used. Open comments were analysed by thematic analysis. STROBE Standards guidelines for cross-sectional studies were followed, and COREQ guidelines were followed for writing qualitative research. The study findings demonstrated that the more clinical experience the nurse practitioner had, the higher their levels of clinical autonomy. The previous length of nursing experience did not impact nurse practitioner clinical autonomy levels. However, average experience of nurse practitioner' in this study was 3-10 years. No significant differences existed between the reported gender, nurse practitioners' clinical autonomy and decision-making. 1:40 female and 1:9 male nurse practitioners undertook a doctorate or PhD-level education. No advanced nurse practitioner identified as non-binary. Gender and organisational culture considerations can influence nurse practitioners clinical autonomy. This study highlights intrinsic motivators that support nurse practitioners in providing innovative healthcare: competence, relatedness and clinical autonomy. Countries credentialing, regulations professional standards and healthcare policy positively influence nurse practitioner clinical autonomy. Nurse practitioners' clinical autonomy is championed when health policy and organisational stakeholders intrinsically collaborate. A disconnect between health policy organisational culture extrinsically influences lower levels of nurse practitioners' clinical autonomy. The findings underline the positive impact of nurse practitioner clinical autonomy. A recommendation of this study is to continue to measure impact of clinical autonomy anddevelop nurse practitioners' self-determination strategies around the role and integrity of their levels of intrinsic clinical autonomy.