This study looked into how public spending impacts financial accountability in Rivers State, Nigeria, focusing specifically on auditing systems, budget transparency, and mechanisms for tracking expenditures. Using a descriptive and explanatory research design, the study carefully documented existing accountability practices while also exploring the causal links between how expenditures are managed and the resulting accountability outcomes. The research involved a population of 1,950 finance and budget officers, auditors, members of the Public Accounts Committee, and civil servants from various Ministries, Departments, and Agencies (MDAs). By applying Yamane’s (1967) formula, a sample of 332 respondents was scientifically selected through stratified and simple random sampling techniques to ensure a fair representation. Primary data were gathered using a structured questionnaire aimed at capturing trends in public spending, transparency measures, and monitoring systems. The data analysis was performed using SPSS version 25, utilizing descriptive statistics to summarize the responses and multiple regression analysis to test the study's hypotheses. The findings showed that public expenditure significantly positively affects auditing systems (R² = 0.986, β = 0.993, p < 0.05), budget transparency (R² = 0.988, β = 0.994, p < 0.05), and expenditure tracking mechanisms (R² = 0.959, β = 0.979, p < 0.05). These results suggest that enhancing public expenditure management greatly improves the effectiveness of financial accountability structures in Rivers State. The study concludes that strengthening expenditure processes promotes transparency, ensures thorough auditing, and enhances expenditure tracking, all of which are vital for sustainable fiscal governance. It recommends that government institutions focus on effective budget implementation, regular audits, and strong expenditure tracking systems.