This study aims to examine the mediating effect of shame, moderated by subfactors of the supervisory relationship (i.e., safe base, reflective education, and structure), on the causational relationship between evaluative concerns perfectionism and supervisory satisfaction of play therapists. The subjects of this study is 197 play therapists with experience of working at child counseling centers in South Korea, each with the minimum of three supervision sessions. Data analysis was conducted using SPSS 26.0 and Hayes’s Process Macro ver. 4.2. The results revealed a significant correlation of evaluative concerns perfectionism, shame, supervisory relationship (i.e., safe base, reflective education, structure), and supervisory satisfaction. The study also found that shame, moderated by subfactors of the supervisory relationship, mediated the relationship between evaluative concerns perfectionism and supervisory satisfaction. Furthermore, reflective education and structure of the supervisory relationship demonstrated an essential moderated mediating effect. This study suggests that to mitigate the adverse impact of evaluative concerns perfectionism on supervisory satisfaction through shame, it is imperative to provide systematic and structured supervision, accompanied by appropriate feedback that fosters internal reflection.