Although there has been a great deal of research on L2 writing in higher education over the past few decades, limited attention has been given to secondary students' writing motivation and engagement in L2 writing contexts. The present study aims to examine the association between writing instructional approaches and student writing motivation and engagement in the Chinese EFL context, and investigate the mediating role of writing feedback in this relationship. 2,169 students from 35 secondary schools in mainland China participated in this study. Results showed that product-oriented teaching approach related positively to the three indicators of maladaptive motivation (i.e., anxiety, failure avoidance, and uncertain control) and process-oriented teaching approach related positively to the two indicators of adaptive engagement (i.e., task management, persistence). While genre-oriented teaching approach related positively to adaptive motivation and engagement, and related negatively to maladaptive motivation and engagement, cooperative multimedia writing teaching approach related negatively to adaptive motivation and one factor of adaptive engagement (i.e., task management), and related positively to two factors of maladaptive motivation (i.e., anxiety, failure avoidance) and maladaptive engagement. This study also identified the mediating role of four feedback practices (i.e., learning-oriented feedback, expressive feedback, computer-mediated feedback, and peer and self feedback) in the associations between writing instructional approaches and student writing motivation and engagement. This study provides insights into our understanding of the complex relationship among teachers' instruction, classroom feedback practices, and student writing motivation and engagement in L2 school contexts.