Many studies have examined the effects of robotics competitions, but few have investigated their effects on participants, especially from the perspectives of students, parents, and coaches. The researchers of this study developed and validated an instrument for exploring the impact of the World Robot Olympiad (WRO), a major international robotics competition, on participants from the perspectives of students, parents, and coaches. Through a literature review and expert discussion, the researchers proposed the first version of the questionnaire. After three years of data collection and three iterations as well as a reliability and validity analysis, factor analysis, and expert review, researchers developed an impact questionnaire for participants in WRO, which included 18 items in the following six dimensions: Learning Skill, Engineering Thinking, Emotional Engagement, Career Choice, Cooperative Solution, and Global Consciousness. Data from 636 valid responses revealed that the questionnaire has good reliability and validity and that students, parents, and coaches all highly valued the positive impact of WRO in 2019. Data analysis indicated that, by and large, students’ abilities have improved in various dimensions which were similar to those of previous research on robotics education and robotics competitions.