Examining ways of reducing physical inactivity has been at the forefront of public health research. Moreover, valid and reliable scales are needed to objectively assess physical activity (PA) avoidance. Previous research has shown that experiencing weight stigma and physical appearance-related concerns are associated with physical inactivity. However, there is currently no Thai instrument that assesses physical inactivity in relation to weight stigma. Therefore, the present study examined the psychometric properties of the Thai version of the Tendency to Avoid Physical Activity and Sport Scale (TAPAS). Thai university students (N = 612) recruited via convenience sampling completed an online survey using SurveyMonkey between September 2022 and January 2023. Confirmatory factor analysis (CFA), multigroup CFA, and Pearson correlations (between TAPAS scores, age, body mass index, and time spent exercising) were used to analyze the data. The CFA showed robust psychometric properties for the Thai version of TAPAS regarding its unidimensional structure. The TAPAS was measurement invariant across sex, weight status, and daily hours of exercise. However, no significant Pearson correlations were found. In general, the results showed that the TAPAS is a good scale for assessing PA avoidance among Thai young adults across different sexes, weight status, and daily hours of exercise.