Objectives: To provide a range of standard evidence-informed recommendations for the primary prevention of mental health problems at work. Methods: Occupational health experts and practitioners evaluated systematic reviews of primary-prevention measures for occupational mental health. A series of consensus meetings were held with the intent of developing primary-prevention guidelines for mental health at work. Results: Three preventive strategies were developed: self-care training, supervisor training, and improving the workplace environment. The guidelines for self-care training consist of four steps that coincide with the process of formulating and implementing measures to help individuals cope with stress (self-care) in the workplace: planning and preparing, deciding what self-care entails, selecting the forms of self-care, and making subsequent efforts. Six recommendations and four tips are provided for these four steps. The guidelines for supervisor mental health training have four categories: selection of training participants, content, delivery format, and frequency. Based on recent findings, we provided recommendations for the content that should be included in training. Training has been shown to improve supervisors' knowledge, attitude, confidence, and behaviors in supporting employees with mental health problems. For improving the psychosocial work environment, 12 items were compiled, including eight recommended items and four tips in four categories: planning and organization development, implementation regarding the basic rules of procedures, proposals for effective improvement measures, and continued implementation. Conclusions: Based on the best evidence currently available, we propose guidelines for primary prevention for mental health at work.