The main purpose of this study was to examine the multi-functional relationship among pre-service teachers' art appreciation, attitude toward science, technology acceptance, creative convergence competency, and teaching competency in STEAM education. Data were collected from 238 pre-service teachers in Korea and were analyzed using structural equation modeling. The results indicate that pre-service teachers' art appreciation, attitude toward science, and technology acceptance had a significant effect on their creative convergence competency. In particular, their attitude toward science had the greatest effect on the creative convergence competency, which had a significant effect on the teaching competency in STEAM education. In addition, individual characteristics (i.e., art appreciation, attitude toward science) had indirect effects on the teaching competency in STEAM education mediated by the creative convergence competency. Overall, the results of this study show the criticality of supporting pre-service teachers to develop positive attitudes toward art appreciation and science to foster creative convergence skills. In conclusion, we suggest that the current fragmented approach with strict disciplinary boundaries at teaching education institutions does not adequately prepare pre-service teachers to be competent in teaching STEAM education. More holistic and systemic approaches are necessary to support the trajectory of pre-service teachers' development of STEAM teaching competency.