This study aims to classify groups of Korean seafood export companies according to their performance levels after obtaining international certifications and to compare and analyze the characteristics of each group. A survey was conducted targeting seafood export companies that possess international certifications. Cluster analysis was performed using 25 performance-related variables associated with international certification outcomes. Subsequently, analysis of variance, independent sample t-tests, and cross-tabulation analyses were conducted to examine differences between the groups. The results identified two clusters based on the level of international certification performance: a high-performance group and a low-performance group. The high-performance group showed higher levels of satisfaction across both financial and non-financial performance outcomes after acquiring international certifications. In particular, significant differences between the two groups were observed in customer-related performance as well as quality and process performance. This group also tended to perceive the importance of certification acquisition factors more strongly and demonstrated greater sensitivity to market requirements, such as overseas buyer demands. In contrast, the low-performance group reported relatively lower satisfaction with certification outcomes and showed higher sensitivity to certification acquisition costs. In terms of firm characteristics, the high-performance group consisted of firms that were relatively recently established and had obtained international certifications more recently, and they were more likely to have dedicated trade departments. Meanwhile, the low-performance group included a higher proportion of firms with larger numbers of employees and greater sales volumes. These findings suggest that the performance outcomes of international certifications are not determined solely by firm size or years of operation but are closely related to firms’ perceptions of certification, their strategic responses, and the organizational capacity to manage and utilize certifications effectively. This study contributes to the literature by empirically demonstrating that heterogeneous groups exist among firms holding international certifications in terms of performance outcomes.