The study investigated principals’ financial management practices for effective administration of public senior secondary schools in Port Harcourt metropolis. Three research questions and three null hypotheses guided the study. A descriptive survey research design was adopted by the study. The population of the study comprised 76 principals (45 males and 31 females) in the 76 public senior secondary schools in Port Harcourt metropolis, comprising Port Harcourt, Obio-Akpor, Emohua, and Ikwerre Local Government Areas. The sample size of the study was the entire population of 76 respondents taken as census without sampling due to its manageable size. The instrument for the study was a self-structured questionnaire tagged “Principals’ Financial Management Practices for effective Administration Questionnaire (PFMPEAQ)”. The questionnaire was validated and its reliability established at 0.80 using Pearson r. The research questions were answered using mean and standard deviation while the hypotheses were tested using z-test at 0.05 level of significance. The findings the study revealed among others that there was no significant difference in the mean responses of male and female principals on the ways in which their financial accounting enhance effective administration of public senior secondary schools in Port Harcourt metropolis. The study concluded that when the right financial management practices are adopted in the effective administration of secondary schools, school administrators manage school finances efficiently and effectively administer their schools. It was recommended among others that school heads should ensure that their school account books are regularly audited to prevent errors and the purchase of school facilities should go through due process of monetary approval before execution.