AimThe study aimed to determine the relationship between general nurses' mental health literacy and beliefs toward mental illness. MethodThe study involved 285 nurses aged 23 to 47 from three hospitals in western Turkey, who completed the Mental Health Literacy Scale (MHLS) and the Beliefs Toward Mental Illness Scale (BMIS) between December 2023 and March 2024. ResultsThose who received training on mental illnesses as students (t = 2.115, p = 0.018), those who had moderate knowledge about mental illnesses (F = 8.177, p < 0.001), those who were willing to receive training on mental illnesses (t = 1.673, p = 0.048), those who encounter individuals with mental illness in their work units (F = 11.233, p < 0.001) and those who care for individuals with mental illness in their work units (t = 1.808, p = 0.036) have higher mental health literacy levels. There was a negative relationship between nurses' negative beliefs toward mental illness levels and their mental health literacymental health literacy levels (r = −0.432, p < 0.001). ConclusionMental health literacy is a crucial element in reducing general nurses' negative beliefs about mental illnesses. Thıus, psychiatric mental health nurses can actively prevent negative beliefs and increase awareness by providing mental health education to general nurses. Awareness programs should be accorded greater emphasize on individuals who are not trained in mental disorders when they are students, those who have low knowledge about mental disorders, those who are reluctant to receive training on mental disorders, and cohorts of nurses who are likely to encounter patients with mental disorders in their respective work units.