BackgroundTeachers' instructional quality is critical to student learning and development. However, the affordance of different aspects of instructional quality remains underexplored.AimsThis study explores the relationship between teachers' personal growth initiative (PGI) and teacher engagement and instructional quality.SampleThe data were collected from 998 teachers (82.9% female, average years of teaching experience = 15.25, SD = 10.29) from China.MethodsThe participants completed an anonymous online survey questionnaire that examined their PGI, work engagement and self‐reported instructional quality. Structural equation modelling and bootstrapping were performed to determine the differentiated associations between PGI and each aspect of the teachers' self‐reported instructional quality.ResultsThe results confirmed the critical role of PGI in teacher engagement and self‐reported instructional quality. To varying degrees, the dimensions of teacher engagement, except for cognitive engagement, mediated the association between PGI and self‐reported instructional quality.ConclusionsThe teachers' self‐reported data showed that their motivation for personal growth played an important role in improving their instructional quality. The teachers' emotional engagement and social engagement with colleagues were positively related to classroom management, and their social engagement with students was associated with a supportive climate.