This study aimed to use a game-based learning (GBL) module with multi-scaffolding and mobile technology for high school students with mild intellectual disabilities (MID) to assist them in learning career education knowledge. This study used a quasi-experimental method to investigate the participants' learning effectiveness, motivation, flow state, game acceptance, and learning behavior patterns (LBP). The differences in the LBP of the high and low learning effectiveness groups and the high and low flow state groups were also investigated. In total, 32 high school students with MID participated in this study. The results show that the GBL module with the multi-scaffolding mechanism could improve their learning effectiveness, motivation, flow state, game acceptance, and LBP and reduce their distraction behavior in the learning activities. The results of the sequential analysis indicated the significance of the behavior of reflection and discussions in the high learning effectiveness group. Additionally, the high-flow state group tended to try multiple strategies to complete the learning tasks. Furthermore, the game mechanism embodied collaborative peer interaction; even when the high-flow group became distracted, they returned to the tasks and continued the discussions with peers.