Working in demanding settings increases the likelihood that psychiatric mental health nurses would feel stressed and less flexible. They work directly with patients who have mental illnesses and deal with challenging situations such patient seclusion, suicide attempts, and verbal and physical abuse that can lead to feelings of guilt, fear, and inflexibility. Therefore, the aim of this study was to ascertain the effects of a stress management education program on the psychological adaptation of Saudi psychiatric nurses. In the current study, a quasi-experimental research approach was used. Based on the inclusion and exclusion criteria, a purposive sample of eighty psychiatric nurses was selected. Forty nurses were randomly selected for the intervention group. Two instruments that measure nurses’ personal information and psychological adaptability were used to gather data for the current investigation. The findings showed that psychological adaptation before and after a stress management education program differed statistically significantly. In conclusion, stress management education program increases the psychological adaptability of nurses. Regular assessments and training programs can help foster a healthy work environment and improve the mental health of the nurses.