Engineers are responsible for solving highly complex problems and, hence, some training to solve such problems, particularly real-life issues, are necessary. The Engineering Accreditation Council (EAC), Board of Engineering of Malaysia (BEM), emphasizes the important of engineering competencies in engineering Program Learning Outcome (PLO), such as the ability to identify, formulate, analyze, and apply mathematical knowledge to engineering problems. However, it was reported that students in university face more challenges in understanding engineering mathematics as they are not taught by instructors who specialize in the respective field. Thus, this study was conducted using a phenomenological approach to identify the mathematical competencies (MC) among practicing engineers at manufacturing workplaces in PDCA (Plan-Do-Check-Action) process workflow. Three respondent engineers were chosen as respondents for this study, but only one respondent reported in this study. Data was gathered through intensive interview sessions at the workplace. Data analysis technique of phenomenological reduction was primarily utilized in this study were Epoche, identify significant statement, Meaning Units, Textural Description of the Experience, Structural Descriptions of the Experience, and Textural-Structural Synthesis phenomenology. The method provides logical, systematic, and coherent design elements that lead to an essential description of the experience. The findings revealed that the MC elements frequently used at each stage of the PDCA process are thinking mathematically, problem handling, and mathematical communication. This study will inform instructors to develop mathematical competencies related to real-life problem-solving during teaching and learning in engineering activities and academic programs at their institutions.