Globally, transgender people have been described as a highly marginalised population due to cisgenderism that delegitimises their gender identities and expressions. Despite robust evidence from many countries noting the association of discrimination and stigma for being transgender with heightened mental health risks, qualitative research that examines the nuances of mental health indicators using health equity frameworks has been scant both in Aotearoa/New Zealand and overseas. Using an inductive thematic approach, this paper analysed 222 open-text responses in the mental health section of the 2018 Counting Ourselves: Aotearoa New Zealand, Trans and Non-binary Health Survey. Our findings showed four overarching themes: gender-affirming healthcare, mental healthcare services and accessibility, gender minority stress, and self-affirmation and social support. Participants’ narratives described pervasive gender minority stress experiences in gender-affirming and mental healthcare services, including unmet healthcare needs, lack of competency in healthcare delivery, and pathologisation of their genders. In social settings, our participants commonly reported discrimination and violence, although they also reported that self-affirmation strategies and social support offset the impacts of gender minority stress on their mental health. The current findings indicate the importance of exploring mental health outcomes for transgender people in relation to cisgenderism and resultant gender minority stress.