This study systematically synthesizes empirical literature on strategies, actors, processes, and contexts of value internalization among students (santri) in Indonesian Islamic boarding schools (pesantren). The review is reported using PRISMA 2020 principles insofar as the original review records allow and applies thematic synthesis to a corpus of 40 empirical studies documented in the source manuscript. The findings show that value internalization in pesantren is not produced by a single pedagogical method, but by an ecosystem that combines exemplary conduct (uswah hasanah), habituation of religious and social practices, spiritual and moral guidance, disciplined routines, experiential participation, educational reward and sanction, and intensive social interaction. Kiai and ustaz function as normative and behavioral reference figures, while peers reinforce collective norms through everyday interaction in the boarding environment. Across the reviewed literature, internalization is best understood as a gradual movement from knowing values, to accepting and negotiating them, and finally to embodying them in routine conduct. This review proposes the Pesantren Value Internalization Ecosystem (PVIE), which integrates five elements: value sources, socializing actors, internalization strategies, cognitive-affective-behavioral pathways, and the residential environment as an enabling context. The evidence base, however, is dominated by local case studies and provides limited longitudinal and comparative evidence regarding the durability of internalized values across pesantren typologies. Future research should test the PVIE longitudinally, compare different pesantren models, and strengthen reporting of research design and outcomes.