This study examined the relationship between internal controls and the financial performance of Savings and Credit Cooperative Organisations (SACCOs) in Wakiso District, Uganda. SACCOs play an increasingly important role in Uganda's financial inclusion agenda, yet many face financial distress attributable in part to weak governance and inadequate internal control systems. A cross-sectional survey design was employed, with data collected from 157 respondents including SACCO managers, board members, loan officers, and finance officers drawn from 32 SACCOs in Wakiso District. The Committee of Sponsoring Organisations of the Treadway Commission (COSO) framework guided the conceptualization of internal controls across five components: control environment, risk assessment, control activities, information and communication, and monitoring. Financial performance was measured through portfolio quality (Portfolio at Risk > 30 days), operational self-sufficiency, return on assets, and loan repayment rates. Pearson correlation revealed strong positive relationships between all COSO components and financial performance. The regression model explained 67.2% of the variance in SACCO financial performance (R² = 0.672, F = 53.41, p < 0.001), with control activities (Beta = 0.298) and monitoring (Beta = 0.271) emerging as the strongest predictors. The study concludes that strong internal controls are a critical determinant of SACCO financial performance and recommends capacity building for SACCO boards, adoption of standardised accounting systems, and strengthened external oversight by the Uganda Cooperative Alliance.