This study examined the influence of principals’ instructional leadership, school support, and work motivation on teachers' professional competence in Padang City’s public junior high schools. A sample of 385 teachers was selected, and data were analyzed using PLS-SEM. The results revealed that instructional leadership (β = 0.308, p < 0.05) and school support (β = 0.414, p < 0.05) positively impacted teachers' professional competence. Both instructional leadership (β = 0.359, p < 0.05) and school support (β = 0.434, p < 0.05) also significantly influenced work motivation, which in turn enhanced professional competence (β = 0.467, p < 0.05). The study highlights the critical role of leadership and support in fostering motivated teachers, offering practical implications for policymakers and school administrators aiming to improve teacher quality.