Nursing students in undergraduate programmes exhibit comparable, sometimes higher, levels of poor mental health and substance use compared to the general population; however, this area remains under-researched in New Zealand. The study involved 172 nursing students enrolled in the Bachelor of Nursing programme at one tertiary institution in Auckland, New Zealand. Employing a mixed-methodology approach, a 29-question survey comprising both open and closed questions was administered to explore the students' experiences with mental health and substance use, as well as their access to support services. Quantitative data were analysed using SPSS version 29 descriptive statistics, while a general inductive approach guided the qualitative analysis. A significant proportion of participants (75%) reported experiencing emotional distress during their studies, with anxiety being the most prevalent (78.5%). A smaller percentage disclosed substance use (8.1%) including excessive alcohol use, cannabis use, nicotine use, vaping cannabis and some refusal to reveal substance use. Surprisingly, less than 1% (n = 0.6) utilised institutional support services. Three qualitative themes were identified including emotional distress and associated effects, emotional and psychological impacts on nursing students' academic journey and tertiary support systems. The findings highlight the urgent need to address the mental health and addiction challenges experienced by nursing students, given their potential adverse effects on academic success and overall well-being. Urgent action is needed to integrate mental health training into the curriculum and provide faculty support. In this study, the underutilisation and inadequacy of institutional support services signal a need for institutional reforms to provide access and personalised mental health support to nursing students. Providing essential skills and support for student success contributes to the overall well-being of the nursing workforce.