Principal instructional leadership plays a key role in promoting teachers’ professional learning and development. This paper reports the findings of a qualitative study investigating the principal instructional leadership in Vietnamese primary schools from the perspective of teachers and school principals. The study also examined the relationship between principal instructional leadership and teachers’ professional learning and development. The study was conducted at 12 schools across four provinces of Vietnam. Data included in-depth interviews with 12 principals and 24 teachers. Analysis of the data revealed that teacher professional development was highly recognised and respected by both the principals and the teachers. The teachers were generally satisfied with the principal instructional leadership in their professional learning and development. Moreover, the findings showed a positive effect of principal instructional leadership on teachers’ professional learning and development practices. These findings contribute to the body of knowledge on the status quo of principal instructional leadership and its effects on teachers’ professional learning and development. The implications of these findings provide valuable insights for policy-makers to develop appropriate policies and strategies to enhance principal instructional leadership capacity and the effectiveness of teachers’ professional learning.