Survival rates of children with cancer have significantly increased over the last decades in high income countries. However, cancer survivors often face significant long-term adverse effects on physical, psychosocial, and neurocognitive health. The use of Patient-Reported Outcomes (PROs) in clinical trials may help to further optimize treatment regimens to minimize acute and late adverse events. Despite clear recommendations of regulatory agencies, the use of PROs in pediatric clinical trials remains limited. In this article, we discuss the rationale to assess PROs in pediatric clinical trials with a specific highlight on electronic PRO (ePRO) assessment. In addition, we underscore the importance of recent international guideline developments such as the Setting International Standards in Analyzing Patient-Reported Outcomes and Quality of Life Endpoints Data (SISAQOL-IMI) and the CONsolidated Standards of Reporting Trials – Patient-Reported Outcomes (CONSORT-PRO) to improve the robustness of PRO data assessment in pediatric oncology, thus facilitating better patient care and more accurate assessments of treatment effects. Best practice examples for the use of modern technologies in ePRO assessments are presented and potential barriers and challenges are discussed. We conclude that – despite some challenges and barriers – the routine assessment of (e)PROs in pediatric clinical trials has the potential to substantially improve the quality of the trials and facilitate the usability of outcome data. We call for a joint effort to take proactive steps to incorporate PROs into clinical trials in pediatric oncology, thus giving children a voice.