No disease-specific, reliable, and valid self-assessment tools exist for athletes with mild coronavirus disease (COVID-19) to self-return to sports. This study aimed to develop a self-assessment screening method for athletes with mild COVID-19. Item generation, item reduction, and pretesting were used to develop a questionnaire that served as a screening tool to detect severe post-COVID-19 complications. The questionnaire was validated by both internal and external reviewers, and the final version consisted of 11 items. Face validity was assessed through direct interviews with 11 athletes. Severe COVID-19 complications were identified for criterion validity and correlation analysis. A total score of 11 indicates that there is no risk of severe COVID-19 complications and gradual return to play is recommended; results <11 indicate a need for further evaluation by trained medical personnel. For reliability test, 50 respondents were chosen and asked to answer the questionnaires 7 days after their first responses. Physical Activity Readiness Questionnaires for post-COVID-19 athletes (PAR-COVID-Q) demonstrated excellent internal consistency (r=1, P<0.05) and test-retest reliability (r=1, P<0.05). A total of 118 athletes scored 11, had normal health screening, normal electrocardiogram and chest X-ray, and successfully returned to sports without any reported complications (r=1, P<0.05). Two athletes scored <11 and underwent further medical evaluation. The PAR-COVID-Q is a valid and reliable self-assessment tool with a low burden for athletes to return to sports following mild COVID-19.