This study aimed to identify how the social competence of elementary school students who participated in sports activities during the COVID-19 affects happiness through interpersonal ability. For this purpose, a total of 336 people who participated in sports activities for at least 6 months during the corona period as fifth and sixth graders of elementary school in Icity were surveyed. The collected data were subjected to descriptive statistical analysis, exploratory factor analysis by variable, reliability, correlation analysis, and hierarchical regression analysis using SPSS PC version 28.0. The research results were as follows. First, there was a statistically significant correlation between social competence, interpersonal ability, and happiness of elementary school students who participated in sports activities. Second, social competence of elementary school students participating in sports activities has a statistically significant effect on interpersonal ability and happiness. Third, interpersonal ability (problem-solving ability and communication ability) has a mediating effect on the effect of social competence (initiative and helping) on happiness (self-happiness and friends’ happiness) of elementary school students who participated in sports activities in the corona situation. However, self-happiness, two sub-variables of happiness, showed a positive (+) influence, whereas the friends’ happiness had a negative (−) influence, indicating that the direction of the influence was different.