Teacher self-efficacy plays an important role in shaping instructional practices and supporting student learning, particularly when teaching multilingual learners (MLs) with disabilities. This mixed-methods study examined variations in teachers’ self-efficacy across the domains of classroom management, instructional strategies, and student engagement at different career stages. Using the Teachers’ Sense of Efficacy Scale (TSES; Tschannen-Moran & Hoy, 2001) and semi-structured interviews, the study explored teachers’ perceived preparedness and professional development (PD) for supporting MLs with disabilities, as well as the alignment between their self-efficacy scores and qualitative insights. Quantitative data from 122 teachers indicated that early-career teachers reported the lowest self-efficacy (M = 4.60, SD = 0.73), mid-career teachers reported moderate self-efficacy (M = 5.34, SD = 1.03), and late- and very-late-career teachers demonstrated the highest levels (M = 5.74, SD = 1.17; M = 5.67, SD = 1.00, respectively). Qualitative interviews with eight participants emphasized the importance of structured routines, relational classroom management, and culturally responsive practices in fostering confidence. However, gaps in training and institutional support remained particularly challenging for early-career educators. Findings contribute to the growing body of research on how teachers’ self-efficacy develops across career stages and how professional learning experiences shape their capacity to meet the needs of MLs with disabilities.