In this study, an explanatory sequential design was utilized to examine the impact of strategy-based instruction (SBI) on the writing performance and motivation of English as a Foreign Language (EFL) learners in a writing course. A total of 50 Chinese EFL students were selected from two intact classes and were randomly assigned to either the control group (n = 24) or the experimental group (n = 26). The experimental group received a sixteen-week metacognition training program integrated into the writing course, while the control group was provided with conventional writing instruction. Data collection was performed through timed writing tasks, a second language writing motivation scale, and semi-structured interviews. The results indicated that the experimental group exhibited a significant improvement in both writing performance and motivation, in comparison to the control group. This study provides empirical evidence for the benefits of SBI in promoting students' writing competency and motivation. The findings have important implications for researchers and educators in the field of EFL writing instruction.