Project management uses many tools, techniques, and methodologies in project development. PRINCE2 methodology set documentation which must be tailored to suit the occasion project. Since software projects may often fail due to lack of well-structured project management method, it is necessary to identify the key success factors of PRINCE2 method in software development project. The purpose of this research study is to identify key success factors of PRINCE2 project management method in software development project. The researcher undertakes a case study in an organisation where software project is implemented in PRINCE2 project management method. Data has been collected from questionnaires and face-to-face interviews. Documents review, and observation techniques were used as secondary data collection sources. The researcher has conducted template analysis with interview data and excels analysis with the questionnaires data. The researcher has then triangulated the data to get authentic and accurate findings. 20 factors have been identified as key success factors in this research study such as defined roles & responsibilities, scope management, manage by stages, well planning, top management support, time management, risk management, monitor project progress, change management, communication management, quality management, project team competency, managing product delivery, cost management, learn from experience, prioritizing task, assign work to right person, benefit realisation and being agile.