To date, inadequate funding remains a major challenge to effective school administration. This necessitates the adoption of proper financial management strategies to enhance the attainment of school goals. This study examined the relationship between administrators’ financial management strategies and school system effectiveness. The main objective was to assess the relationship between financial planning strategy, financial expenditure control strategy, and the effectiveness of private secondary school system in Cross River State, Nigeria. The study adopted a correlational research design. The population consisted of all 295 private secondary schools in Cross River State, and a census approach was employed to ensure comprehensive coverage. Data was collected using a validated questionnaire titled “Financial Management Strategies and Secondary School System Effectiveness Questionnaire (FMSSSSEQ)”, assessed by three experts in Educational Management, Test, Measurement, and Evaluation. The instrument’s reliability was established through Cronbach’s Alpha, yielding coefficients of .77 and .81. Responses were scored on a four-point Likert scale and analyzed using Pearson Product-Moment Correlation in SPSS v26 at a 0.05 significance level. The findings revealed a statistically significant relationship between financial planning strategy, financial expenditure control strategy, and school system effectiveness. The study concluded that administrators' financial management strategies significantly relate to the effectiveness of the secondary school system in Cross River State, Nigeria. The results highlight the importance of financial planning in setting clear budgets, prioritizing expenditures, and aligning resources with educational goals. Additionally, effective expenditure control promotes accountability, reduces waste, and optimizes resource use, which ultimately improve school system effectiveness. The study recommended that the state government through the ministry of education should organize a capacity-building programs for school administrators to improve their financial planning competencies, so as to promote better financial management and overall school performance.