This study assessed the physical activities of Mental Health Nurses (MHN) in New Zealand against the 2018 World Health Organization recommended minimum levels of moderate‐to‐vigorous physical activity. The research design was exploratory and descriptive as there were no previous studies about physical activity levels of MHNs in New Zealand. Quantitative and qualitative data were collected using the International Physical Activity Questionnaire (IPAQ, Long Version) which included options for free‐text responses. Data were analysed using descriptive and inferential statistics. A total of 266 participants returned the survey, a response rate of 4%, and a limitation of the study. More than 50% of MHNs reported <150 min of moderate‐to‐vigorous exercise per week for each of the four physical activity domains. When individual physical activity domains were combined, only 10% spent <150 min on moderate‐to‐vigorous physical activity. Work‐related physical activities were higher for those working in the inpatient area than in community settings. Transport‐related physical activities were higher for those working in community settings. Participants registered from 6 to 20 years had more time sitting than other groups. Nurses aged 55 years and above showed the highest total physical activity levels. Moreover, healthcare organizations and nurse leaders need to promote physical activity and provide wellness intervention for their staff. Nurses who are physically active may be more effective in supporting their patients to increase their physical activity.