Recently, self-leadership has drawn great attention as important leadership that employees have through effects for the sustenance and growth of an organization. Therefore, this study attempted to provide basic data and information needed for hair cosmetology jobs after investigating the effects of self-leadership on service flexibility, expression of positive emotions, and job performance amongst beauty salon workers. For data analysis, the following were performed with SPSS v. 21.0: frequency analysis, factor analysis, reliability analysis, estimation of Cronbach’s alpha, correlation analysis, linear regression analysis, and three-step mediated regression analysis. In terms of research subject and scope, a total of 266 questionnaires were analyzed amongst beauty salon employees in Gwangju Metropolitan City from October 5 to November 7, using a five-point Likert scale. The results found the following: Self-leadership had an influence on service flexibility, expression of positive emotions, and job performance; service flexibility affected the expression of positive emotions and job performance. In addition, service flexibility played a mediating role between self-leadership and expression of positive emotions/job performance. Therefore, beauty salon owners need to help their employees display and fulfill self-leadership freely. Furthermore, it is required to encourage autonomous and creative services and grant authorities and responsibilities to achieve ‘service flexibility.’