Clinical simulation can be a promising teaching strategy to help nurses develop behaviors that improve family care actions, promoting safe and high-quality care. The objective of this study was to build, validate, and test a simulation scenario in pediatric oncology family-focused care (FFC) following an initial diagnosis of cancer. It is a six-step methodological study based on the philosophy of Family-Centered Care (FCC), with a user-centered design. The evaluators established a Content Validity Index (CVI) > 0.8 for validation. Pilot testing included the Simulation Design Scale. The data were analyzed by descriptive statistics. A total of 35 experts participated in this study. All 19 items in the scenario were validated and considered relevant, in a single round, with the item-level CVI ranging between 0.8 and 1 and a scale-level CVI of 0.92. The high-fidelity developed and validated clinical simulation scenario is a consistent tool for the education of advanced practice nurses.