<p>A central challenge in contemporary play-based curricula is supporting teachers to enact high-quality play support consistently across diverse center conditions. Guided by the Job Demands–Resources (JD-R) framework, this study examined how teacher self-efficacy (Level 1) and center-level physical and psychosocial work environments (Level 2) jointly predict teachers’ play support. Survey data were collected from 300 teachers nested within 100 childcare centers in South Korea. Two-level random-slope models estimated direct and interactive effects while controlling for teaching experience, classroom age, child–teacher ratio, education level, and center type. Both physical and psychosocial environments were positively associated with play support, and teacher self-efficacy also predicted play support. Crucially, cross-level interactions were significant: the association between self-efficacy and play support was evident in average and high-quality environments, but not in low-quality settings. These findings indicate that the effects of teacher self-efficacy are not universal but contingent upon organizational conditions, with work environments functioning as contextual enablers or constraints on the enactment of play support. Practically, the results highlight the need for a dual strategy: strengthening teachers’ self-efficacy through targeted professional learning while investing in well-designed physical settings and collegial, growth-oriented climates. Aligning individual motivation with supportive work environments is essential for sustaining high-quality play-based instruction across centers.</p>