Interest in the practice of gamification has grown rapidly in the field of education and training. Organisations implement gamification in various areas to boost employee motivation, including professional training. The present study comprises a systematic literature review on gamified professional training among employees. It was guided by the Preferred Reporting Items Systematic Reviews and Meta-Analysis (PRISMA) 2020 checklist. The articles reviewed were obtained from three large academic databases -- Scopus, Web of Science, and PubMed, with Google Scholar as a supporting database. The analysis revealed that most studies did not discuss gamified professional training from theoretical perspectives. Three main strategies for gamifying professional training were identified -- gamified professional training platform, blended gamified professional training, and face-to-face gamified professional training. It was found that achievement game elements were common in gamified professional training. The most frequent digital game elements were points/levels, leaderboards, challenges, and badges. Real-world rewards were also highly popular. Practical applications and research directions for researchers, instructional designers, and programme developers were then suggested to implement future gamified professional training.