This study aimed to investigate the factors influencing mental health nurses' attitudes towards people with mental illness. A descriptive correlation design was used. A sample of 180 Taiwanese mental health nurses was recruited from mental health‐care settings. Data were analyzed with descriptive statistics, Pearson's product‐moment correlation, Student's t‐test, one‐way anova, and a hierarchical multiple regression analysis. Negative attitudes were found among mental health nurses, especially with respect to individuals with substance abuse compared with those with schizophrenia and major depression. Mental health nurses who were older, had more clinical experiences in mental health care, and demonstrated greater empathy expressed more positive attitudes towards people with mental illness. Mental health nurses working at acute psychiatric units demonstrated more negative attitudes towards mental illness compared with those working in psychiatric rehabilitation units and outpatient clinics or community psychiatric rehabilitation centres. Particularly, length of mental health nursing practice and empathy significantly accounted for mental health nurses' attitudes towards mental illness. Understanding nurses' attitudes and their correlates towards people with mental illness is critical to deliver effective mental health nursing care.