Robotic competitions have become an increasingly popular educational tool to increase students’ interest and achievement in STEM. The largest and fastest growing of these is VEX Robotics Competitions (VRCs). Although millions of dollars of funding are allocated, and countless hours of effort are expended annually to provide students with the opportunity to compete in VRCs, little research has been done to investigate the educational impacts of participation in these competitions. One promising research framework in this area is to investigate the self-efficacy of students who participate in VRCs. Self-efficacy, or the beliefs one holds about one’s own abilities in a given area, has been shown to have a strong influence on students’ career and educational interests, choices, and attainment. The purpose of this study was to investigate two research questions: (1) What factors influence VEX Robotics Competition participants’ self-efficacy? (2) What is the relationship between self-efficacy in VRCs and students’ interest in and choice of STEM majors? A cross sectional study was conducted utilizing Robinson’s Self-Confidence Survey for VEX Robotics Participants (SCSVRP) to measure VRC participants’ self-efficacy. In addition, the Post-Secondary Choices Survey was utilized to gather data about the relationship between VRC participants’ self-efficacy and their post-secondary educational choices. Study participants were recruited over a period of 3 years at state- and national-level VRCs, as well as through nationwide recruitment efforts assisted by the CREATE Foundation. A total of 390 students participated in the SCSVRP, while 28 students participated in the Post-Secondary Choices Survey. Correlation and regression analyses were conducted to investigate the relationship between several predictor variables and overall self-efficacy. Correlation analysis was conducted to investigate the relationship between VRC participants’ self-efficacy and their choice of major upon enrolling in post-secondary educational programs. The results indicated that VRC participants’ self-efficacy was primarily influenced by their biological sex and the number of seasons they had participated in VRCs. In addition, self-efficacy was correlated with students’ interest in choosing engineering majors, but not STEM majors more generally. Finally, a statistically significant relationship was found between self-efficacy and VRC participants’ actual choice of STEM majors, but not engineering majors specifically.