Background: The public health workforce (PHW) needs to have the necessary capacities to provide healthcare services and public health services. Training needs assessments (TNA) is necessary to assess and understand PHW and their capacities to provide services. This review attempts to identify and describe published studies on tools and methodologies for TNA of the workforce used in public health and health-related fields. Methods: A systematized review of literature was carried out in February 2022. Cochrane Handbook for systematic review version 5.2.0 and PRISMA 2020 statement were used to guide reporting. This review includes original research, reports and grey literature from the websites of public health organizations in English. Results: This review included 38 documents for evidence synthesis. Twenty-seven documents were indexed literature (71%) and 11 were grey documents (29%). TNA documents were published between 1999 and 2022. TNA was performed in many countries around the world. The organizations used either a validated questionnaire or created their own tools to perform organizational and individual self-assessments. The TNA tools were developed using different methods such as expert panels, literature reviews, stakeholder interviews and quantitative surveys. Conclusion: TNA is useful for defining and characterizing the public health workforce in every organization. Workforces consist of individuals who have their own training needs to fulfill their tasks. Therefore, individual and organizational TNA should be combined to study the public health workforce and their capacities.