Sex workers are among the most stigmatised people globally, with sex workers in Vietnam being no exception. Self-stigma affects sex workers adversely, harming psychological health and acting as a barrier to seeking health care. To inform programmes and interventions to improve well-being, identifying unhelpful or negative core beliefs may provide the basis from which individuals can be supported. With this in mind, this study aimed to gain the perspective of sex workers in Vietnam on the contexts of their working lives. Data were collected in Hanoi. Fourteen semi-structured interviews were conducted with Vietnamese sex workers over the age of 18 who were working or formerly worked in Vietnam. Data were analysed manually, informed by theoretical models of self-stigma using inductive thematic analysis. The analysis identified negative/unhelpful core beliefs (disclosure, self-stigma and shame, sexuality, sexual pleasure relationships, health care); contextual life circumstances (sex work, violence, traditional education); and coping mechanisms (problem-focused coping, emotion-focused coping). Findings identify the importance of core beliefs in understanding self-stigma, paving the way for programmes and interventions to address self-stigma among sex workers.