Background: Educational robots are regarded as effective learning tools in science, technology, engineering, and mathematics (STEM) education, and educational robotics competitions have become highly popular. Objectives: This study investigated the effects of participation in an educational robotics competition, the World Robot Olympiad, from the parent's perspective. Methods: This study collected and analysed 128 questionnaires and 30 interviews of parents from different countries. For quantitative studies, descriptive and correlation analyses were employed. For qualitative studies, grounded theory was used to generate codes and categories. The quantitative and qualitative analyses were then combined to comprehensively evaluate the findings. Results and Conclusions: According to the quantitative research results, parents agreed that participation in the WRO can positively influence their child's abilities in seven dimensions, with emotional engagement receiving the most influence. The qualitative results indicated that parents perceived advancements in not only their child's STEM knowledge on specific topics but also noted effects on their learning performance in school and choice of career. This study proposed the use of the Expectation-Effort-Impact model from the parent's perspective. The virtuous cycle between the child's efforts to perform well and the parent's expectations of growth exerts a lasting effect on the child's development.