Purpose: To develop an evidence-based decision aid for parents of children with cancer and to help guide them in the use of complementary and alternative medicine (CAM) for cancer care. Methods: This study had a mixed research design. The needs of parents were investigated by survey and focus group. A systematic review and meta-analysis were performed on the effectiveness of CAM using Grading of Recommendations Assessment, Development and Evaluation (GRADE). Clinical experts were interviewed and a decision aid on CAM treatment for pain was developed. Results: Parents emphasized the importance of reliable information on CAM, focusing primarily on communication and a broad spectrum of complaints related to cancer treatment. The decision aid on CAM for pain included five modalities based on 11 randomized control trials (RCTs): hypnotherapy, mind-body techniques, massage, healing touch, and music therapy. Meta-analysis could be performed on hypnotherapy, which significantly reduced cancer-related procedural pain compared with standard care (MD, − 1.37; 95% CI, − 1.60, − 1.15; P < 0.00001) and attention control (MD, − 1.13; 95% CI, − 1.34, − 0.94; P < 0.00001), and massage, demonstrating no effect on pain compared with standard care (MD, − 0.77; 95% CI, − 1.82, 0.28; P = 0.15). Research evidence and supplementary information from clinical practice and patient were incorporated in a website-based decision aid. Conclusions: An evidence-based decision aid was developed to support parents of children with cancer in making decisions about CAM for pain management. Next steps will be to expand the website to include additional childhood cancer-related complaints and to evaluate its use in practice.