Abstract: This paper examines the systems theory of management in modern day organizations with an highlight on an indigenous company based in Port Harcourt. In this work, an introductory perspective was captured to show an understanding of what the systems theory is all about, revealing the input-output model. The paper categorizes the systems theory into two thought areas: the cybernetic and closed systems on one side and the biology and open systems on the other side, and differentiations made. Systems theory focuses on the relations between the parts, rather than reducing an entity into its parts or elements. The organization is considered as a system having integrated parts that must be coordinated for efficiency and effectiveness. The null hypothesis of no relationship between application of system theory of management and organizational success was rejected. The study found that the organization under study adopts systems approach. The study recommends that modern organizations should adapt systems approach to enhance corporate growth and profitability.