Background: Uganda's adoption of a Competency-Based Curriculum (CBC) in 2018 represented a significant shift toward practical skills development and sustainability integration, yet implementation gaps have emerged between curriculum intentions and classroom realities, particularly regarding hands-on learning experiences that develop technical competence and environmental consciousness. Objective: This study examined the potential for embedding Fix-It Labs—innovative repair-based learning spaces— within Uganda's CBC framework as mechanisms for enhancing practical competence development and sustainability education in secondary schools. Methods: A concurrent mixed-methods design was employed across 24 secondary schools in Central Uganda (Kampala, Wakiso, Mukono, and Mpigi). The quantitative component involved surveys of 384 teachers (determined using Cochran's formula to achieve 80% statistical power) and 422 students selected through stratified random sampling, with analyses including descriptive statistics, one-way ANOVA, Pearson correlations, and multiple regression. Results: One-way ANOVA revealed significant differences in CBC implementation fidelity across school contexts (F= 28.64, p < 0.001, η² = 0.131), with urban schools (M = 3.42) significantly outperforming peri urban (M = 3.18) and rural schools (M = 2.76), though sustainability integration remained low across all contexts (overall M = 2.55, SD = 0.82). Correlation analysis demonstrated strong positive relationships between practical learning opportunities and student practical competence (r = 0.679, p < 0.01) and between sustainability integration and student environmental awareness (r = 0.596, p < 0.01), confirming the pedagogical alignment between Fix-It Lab approaches and CBC competency goals. Multiple regression analysis identified resource availability (β = 0.341, p < 0.001) as the strongest predictor of Fix-It Lab integration feasibility, followed by administrative support (β = 0.253, p < 0.001), teacher training adequacy (β = 0.235, p < 0.001), CBC implementation fidelity (β = 0.226, p = 0.002), and school context (β = 0.218, p < 0.001), collectively explaining 61.2% of variance (R² = 0.612, Adjusted R² = 0.605, F(7, 376) = 84.63, p< 0.001). Conclusion: Uganda's CBC framework provided conceptual space for Fix-It Lab integration, and repair-based pedagogical approaches aligned strongly with curriculum competency goals; however, successful implementation required systemic interventions addressing resource disparities (particularly between urban and rural schools), teacher professional development needs, and institutional support structures. Teachers perceived Fix-It Labs as feasible (M = 3.52) and students demonstrated high interest in repair activities (M = 3.92), indicating favorable attitudinal conditionsfor integration despite current structural implementation challenges. Recommendations: The study recommends establishing a national Fix-It Lab implementation framework with tiered resource allocation prioritizing under-resourced schools; developing comprehensive teacher professional development programs for repair-based pedagogy; and integrating Fix-It Lab performance indicators into CBC monitoring systems to ensure sustained attention and accountability.