Proactive employee behaviour (e.g., job crafting) and aligning jobs with abilities, needs, and preferences have been accorded with the potential for several organisationally desirable outcomes. This study addresses two gaps in the existing literature: the lack of empirical research on the inherent predisposition of psychological safety (PS), psychological autonomy (PA), and task competence (TC) to JCB and the limited investigation of the underlying mechanisms in these relationships. This study uses job demands-resources theory to examine the influence of PS, PA, and TC on JCB and the moderating role of job crafting self-efficacy in these relationships. A statistical regression test (aided by Process Micro) was applied to the data. The study found that task competence and psychological autonomy significantly influenced job-crafting behaviour, while psychological safety did not. Job crafting self-efficacy moderated these effects, with psychological safety being more impactful when self-efficacy is low. This study contributes to understanding JCB’s antecedents and boundary conditions, and the job demand-job resource theoretical model is a valuable organisational factor needed to address this knowledge gap, thus providing insights for theory-building and practical interventions. As JCB and its proposed antecedents are malleable, this study highlights the potential resources to improve JCB in the workplace.