In recent years, software companies have shifted from plan-based software development( PBSD) to Agile software development (ASD) for improved efficiency and product delivery, with ASD demonstrating superior benefits compared to traditional approaches. This paper presents an in-depth exploration of an action research study detailing the transition of a software development team from a plan-based paradigm to Agile methodology. The primary goal is to provide a comprehensive account of the Agile transition journey within the context of action research and to underscore the associated benefits derived from this iterative and participatory research approach. Spanning two years, the study progresses through four cycles of iterations, allowing for continuous refinement of the Agile adoption process. Findings derived from the action research study showcase positive and tangible outcomes of the transition to Agile methodology. Notable improvements include heightened deliverable quality, enhanced intra-team communication, strengthened collaboration with stakeholders, and an increased frequency of software releases. Comparative analysis with PBSD highlights Agile advantages, especially in defect trend, the number of releases, defect lifecycle, and total automation percentage. Agile metrics, including the Burndown Chart, Velocity, Say-Do Ratio, In-sprint Automation, Defect Density, Execution Maturity, and Defect-less Stories, demonstrate substantial improvements, reinforcing the effectiveness of the Agile transition process. The study concludes that the transition to Agile methodology demonstrates significant improvements in various aspects of software development. Positive outcomes support the trend of adopting Agile methodologies in the software industry, emphasizing the effectiveness of the Agile transition process.