In Kampala, Uganda, financial organisations and management information systems (MIS) affect decision-making. The study examines how computerised, manual, and system control affect financial institution decision-making. Cross-sectional surveys collect data via questionnaire. A 138-person study with 130 samples. Used statistics include frequencies, percentages, means, and regression. The results suggest that computerised MIS improves decision-making more than manual MIS. Decision-making improves with system control. Computerised MIS provides real-time information, allowing Kampala, Uganda, banks to make better decisions, the study showed. Manual MIS is slow, error-prone, and report-less. The research encourages banks to properly assess their computerised MIS to ensure it satisfies their needs. Implement internal controls to reduce fraud, embezzlement, and errors. A manual should standardise management procedures and processes to ensure financial reporting accuracy.