Background: Pain is a common and distressing symptom in people with cancer, but is under-recognised and under-treated. Australian guidelines for 'Cancer Pain Management in Adults' are available on the Cancer Council Australia Cancer Guideline Wiki. This study aims to evaluate the effectiveness and cost-effectiveness of a suite of guideline implementation strategies for improving pain outcomes in adults with cancer in oncology and palliative care outpatient settings. Methods: The study will use a stepped-wedge cluster randomised controlled design, with oncology and palliative care outpatient services as the clusters. Patients will be eligible if they are adults with cancer and pain presenting to participating services during the study period. During an initial control arm, services will routinely screen patients for average and worst pain over the past 24 h using a 0-10 numerical rating scale (NRS) and have unfettered access to online guidelines. During the intervention arm, staff at each service will be encouraged to use: 1) a patient education booklet and self-management resource; 2) an online spaced learning cancer pain education module for clinicians from different disciplines; and 3) audit and feedback of service performance on key indices of cancer pain screening, assessment and management. Service-based clinical change champions will lead implementation of these strategies. The trial's primary outcome will be the probability that patients initially screened as having moderate-severe (≥5/10 NRS) worst pain experience a clinically important improvement one week later, defined as ≥ 30% reduction. Secondary outcomes will include patient empowerment and quality of life, carer experience, and cost-effectiveness. For the main analysis, linear mixed models will be used, accounting for clustering and the longitudinal design. Eighty-two patients per service at six services (N = 492) will provide > 90% power. A qualitative sub-study and analyses of structural and process factors will explore opportunities for further refinement and tailoring of the intervention. Discussion: This pragmatic trial will inform implementation of guidelines across a range of oncology and palliative care outpatient service contexts. If found effective, the implementation strategies will be made freely available on the Wiki alongside the guidelines. Trial registration: Registered 23/01/2015 on the Australian New Zealand Clinical Trials Registry (ACTRN12615000064505).