The aim of every business organization is to survive amid the competition and the turbulent nature of business environment. The purpose of this study was to examine the relationship between information system development approaches and organizational competitive advantage of business organizations in Port Harcourt, Rivers State, Nigeria. The study adopted the explanatory and quantitative method, hence correlational research design is employed to investigate the correlation between the study variables with target population of 45 respondents as the study population. Krejcie and Morgan determination table was used to derived the study sample size of (40) participants. The closed ended structured 4 points Likert scale Questionnaire was constructed for use in data gathering. Collected data were coded into a format and analysed with the aid of Pearson Product Moment Correlation Coefficient Statistics and presented using Statistical Package for Social Sciences (SPSS) software package for ease of interpretations. The findings showed low and moderate significant relationship between the first dimension of information system development approaches -Waterfall approach and the two measures of organizational competitive advantage – customers’ requirement and business performance. The second dimension of information system development approaches – Agile Management Approach significantly correlates with the two measures of organizational competitive advantage – customers’ requirements and business performance. Therefore, we recommended that, when developing information system for business organizations, the aims and objectives should determine the recommended approach to be used by system developers. Keywords: Information System Development Approaches, Waterfall Approach, Agile Management Approach, Organizational Competitive Advantage