The quality of education in schools is strongly influenced by teacher performance, which directly affects the effectiveness of learning and student achievement. Teacher performance is determined by various factors, including transformational leadership, work environment, and work motivation. The observed decline in teacher performance at Notre Dame School in West Jakarta highlights the importance of examining the relationships among these variables. This study aims to analyze the influence of transformational leadership and work environment on teacher performance, with work motivation as a mediating variable. This research employed a quantitative, non-experimental approach using a causal design and Structural Equation Modeling (SEM) with the aid of SmartPLS 4 software. Data were collected through a five-point Likert scale questionnaire administered to 108 teachers at Notre Dame School Jakarta as respondents. The results indicate that transformational leadership does not have a positive effect on teacher performance (ρ = -0.018), whereas work environment and work motivation have a positive effect on teacher performance (ρ = 0.121; ρ = 0.591). In addition, transformational leadership and work environment positively influence work motivation (ρ = 0.162; ρ = 0.280). Furthermore, work motivation mediates the relationship between transformational leadership and work environment on teacher performance (ρ = 0.096; ρ = 0.165). / Kualitas pendidikan di sekolah sangat dipengaruhi oleh kinerja guru yang berdampak langsung pada mutu pembelajaran dan pencapaian siswa. Kinerja guru ini dipengaruhi oleh beberapa faktor seperti transformational leadership, work environment dan work motivation. Fenomena penurunan kinerja guru di sekolah Notre Dame Jakarta Barat menunjukkan pentingnya mengkaji hubungan antara faktor-faktor tersebut terhadap kinerja guru. Penelitian ini bertujuan menganalisis pengaruh transformational leadership, work environment terhadap kinerja guru melalui work motivation sebagai variabel mediasi. Penelitian ini menggunakan pendekatan kuantitatif non-eksperimental dengan desain uji kausalitas dan metode analisis Structural Equation Modeling (SEM) dengan bantuan SmartPLS 4. Pengumpulan data dilakukan melalui penyebaran kuesioner berskala Likert 5 poin kepada 108 guru di Sekolah Notre Dame Jakarta yang bertindak sebagai responden. Hasil penelitian menunjukkan bahwa transformational leadership tidak berpengaruh positif terhadap kinerja guru (ρ = -0,018) sementara work environment dan work motivation berpengaruh positif terhadap kinerja guru (ρ = 0,121; ρ = 0,591). Transformational leadership dan work environment juga berpengaruh positif terhadap work motivation (ρ = 0,162; ρ = 0,280). Selain itu work motivation memediasi hubungan transformational leadership dan work environmen terhadap kinerja guru (ρ = 0,096; ρ = 0,165).