Providing a favourable practice environment has been regarded as an essential to improve the job outcomes of newly graduated nurses (NGNs). However, little is known about how and when NGNs can best utilize their practice environment to produce optimal job outcomes.The aim of this study, which is based on the Conservation of Resources Theory and the Social Cognitive Model of Career Self-Management, is to investigate whether NGNs who have a higher level of personal growth initiative are more likely to benefit from their practice environment and achieve better job outcomes by increasing their occupational self-efficacy.A cross-sectional study.From 1 September 2022, to 30 September 2022, 279 NGNs from five Chinese state-owned hospitals were recruited for this study. The participants completed measures of practice environment, personal growth initiative, occupational self-efficacy, job stress, job satisfaction, turnover intention and quality of care. A descriptive analysis and a moderated mediation model were computed. Reporting adhered to the STROBE statement.The influence of the practice environment on job outcomes was significantly mediated by occupational self-efficacy, with personal growth initiative acting as a moderator of this mediation effect.NGNs who exhibited a higher degree of personal growth initiative were more likely to derive benefits from their practice environment and attain positive job outcomes by enhancing their occupational self-efficacy. To boost NGNs' occupational self-efficacy and achieve optimal job outcomes, hospital administrators may not only provide a supportive practice environment for them but also conduct interventions that promote their personal growth initiative.This study was designed to examine the psychosocial factors associated with NGNs' job outcomes. The study was not conducted using suggestions from the patient groups or the public.Our findings indicate that favourable practise contexts may not always benefit the nursing job outcome if NGNs do not exhibit a high level of personal growth initiative and produce increased occupational self-efficacy. Therefore, hospital administrators should consider implementing an intervention to improve the personal growth initiative of NGNs so that they can take full advantage of the practice environment and gain resources at work to create optimal job outcomes.© 2023 John Wiley & Sons Ltd.