Introduction Self-oriented perfectionism is the tendency to set high standards for oneself and evaluate one’s behaviour accordingly. Based on a study of 692 students in Korea, Seo (2008) reported finding a negative relationship between self-oriented perfectionism and academic procrastination – i.e., the tendency to procrastinate on academic tasks. Furthermore, Seo reported that this relationship was completely mediated by self-efficacy. Seo’s study has been influential in the literature but to our knowledge has not yet been independently replicated. In this study we report a preregistered conceptual replication testing five hypotheses based on Seo’s key findings. Material and methods A detailed preregistration (including data processing and analysis syntax) was lodged in advance of data collection at https://osf.io/xfvd8. Participants were 575 students recruited from OECD countries using prolific.co. Academic procrastination was measured via an adapted version of the Procrastination Assessment Scale – Students, while self-oriented perfectionism was measured via the 5-item self-oriented perfectionism subscale of the Big Three Perfectionism Scale. Self-efficacy was measured via the New General Self-Efficacy Scale. Both ordinary least squares regression and structural equation modelling were used to test hypotheses. Results We found no evidence of a bivariate relationship between self-oriented perfectionism and academic procrastination in either set of analyses. However, we did find evidence of a small and negative indirect effect of self-oriented perfectionism on academic procrastination via self-efficacy. Conclusions We were only able to partially replicate Seo’s key findings, having found no evidence of a negative relationship between self-oriented perfectionism and academic procrastination.