This study examined the relationship between legislative oversight capacity and perceived corruption levels across district local governments in Uganda, responding to persistent concerns that formal council oversight structures established under the decentralization framework have not translated into commensurate reductions in perceived corruption. A cross-sectional analytical design was adopted, drawing a sample of 653 respondents, comprising district councilors, technical staff, and civil society representatives, nested within 42 purposively and randomly selected districts spanning the Central, Eastern, Northern, and Western regions. A composite Legislative Oversight Capacity Index (LOCI) and a Perceived Corruption Index (PCI) were constructed and analysed using univariate, bivariate, and multivariate statistical techniques, culminating in a mixed-effects linear regression with a district-level random intercept, and complemented by a battery of sensitivity analyses. The mean LOCI was 61.97 (SD = 11.55) and the mean PCI was 50.92 (SD = 11.57), with substantial variation across regions and between urban and rural districts. Bivariate analysis revealed a significant negative correlation between oversight capacity and perceived corruption (r = -0.370, p < 0.001). The multivariate mixed-effects model confirmed that legislative oversight capacity remained a significant independent predictor of perceived corruption after adjusting for respondent and district-level covariates (β = -0.297, 95% CI: -0.379 to -0.214, p < 0.001), with civil society presence, urban location, district revenue per capita, distance to the capital, and political competition also emerging as significant correlates. Sensitivity analyses, including cluster-robust ordinary least squares regression, outlier-exclusion re-estimation, and logistic regression on a binarized outcome, produced consistent effect sizes and directions, confirming the robustness of the central finding. The study concludes that strengthening the practical, resourced capacity of district councils to exercise oversight is a viable and evidence-based entry point for reducing perceived corruption in Uganda's local governance system, and recommends targeted investment in committee capacity, civil society engagement, and support to structurally disadvantaged districts.