The shift toward 21st-century education demands meaningful and competency-oriented learning, making the implementation of deep learning in elementary education increasingly critical despite persistent structural and leadership challenges. This study aims to synthesize empirical evidence on the role of principals’ transformational leadership in supporting deep learning implementation in elementary schools. This study employed a Systematic Literature Review (SLR) with a qualitative-descriptive approach and thematic synthesis following the PRISMA framework. Data were collected from Scopus and ERIC databases through a staged selection process based on inclusion and exclusion criteria, resulting in 13 empirical studies for in-depth analysis. The findings indicate that the four dimensions of transformational leadership—idealized influence, inspirational motivation, intellectual stimulation, and individualized consideration—function complementarily in building teacher trust, mobilizing collective commitment, fostering pedagogical innovation, and supporting contextual professional development. In addition, instructional leadership serves as a key mechanism that bridges transformational leadership with deep learning practices through academic supervision and the strengthening of professional learning communities. The study concludes that successful deep learning implementation in elementary education is highly dependent on transformational leadership enacted systemically and oriented toward sustained pedagogical change.