Abstract Objectives Several studies suggested that CD30 expression is a favorable prognostic marker in transformed mycosis fungoides (tMF). However, evidence in this field is still unclear. This systematic review and meta-analysis aimed to evaluate the prognostic significance of CD30 in tMF. Methods Electronic databases were searched from their inception to June 2020 for all studies assessing the prognostic value of CD30 in tMF. Pooled hazard ratio (HR) for death was calculated; a P value less than .05 was considered significant. Inconsistency index (I2) was used to assess statistical heterogeneity among studies. Results Seven studies with 323 patients were included. CD30 expression in tMF was significantly associated with a decreased hazard of death both on univariate (HR, 0.459; 95% confidence interval [CI], 0.319-0.660; P < .001) and multivariate analysis (HR, 0.503; 95% CI, 0.345-0.734; P < .001), and the statistical heterogeneity among studies was null in all analyses (I2 = 0%). Conclusions tMF cases with CD30 expression in large cells have a hazard of death two times lower than CD30-negative cases.