The focused of this study was human resource planning and organizational effectiveness (a study of deposit money banks in Port Harcourt). The study's goal was to determine how much human resource planning impacts an organization's effectiveness. The study specifically examines the effect of manpower forecasting and employee audit on managerial competence and attainment of objective of selected money deposit banks in Port Harcourt. The secondary source of data collection was adopted since it was more of theoretical review and opinion based. Hence, the information was sourced from journals, article, internet, textbooks etc. The study findings revealed that manpower forecasting has effect on manager’s competence in deposit money banks in Port Harcourt; and there is a relationship between employee audit and attainment of objective in deposit money banks in Port Harcourt. The study comes to the conclusion that a well-planned human resource strategy can help institutions, particularly deposit money banks in Port Harcourt and have qualified employees who are doing the right thing at the right time and in the right place, thereby enhancing or promoting the organization's operational effectiveness. According to the study's findings and recommendations, deposit money banks and their human resource managers should regularly conduct manpower audits and planning to ascertain in advance the demand and supply situation in the labour market prior to hiring employees.