Abstract Sustainable tourism is an important goal within the global sustainable development framework. In sustainable tourism, tourists are expected to behave in an environmentally friendly manner and respect the local culture and economy. However, the level of sustainable behaviour among tourists varies across different regions and countries. This study aims to understand the sustainable tourism behaviour of Vietnamese tourists visiting Ho Chi Minh City, Vietnam. It focuses on (1) the sustainable behaviour of tourists, (2) the correlation between access to sustainable tourism information and sustainable behaviour, as well as participant characteristics and the behaviour; and (3) initial suggestions for promoting changes towards sustainable behaviour among tourists. The study uses a mixed-methods approach, combining both quantitative and qualitative methods. Quantitative data were collected through direct questionnaires from 240 tourists visiting Ho Chi Minh City. Qualitative data were obtained through semi-structured, in-depth interviews with 47 participants. The results indicate three common groups of behaviour related to sustainable tourism during travel: saving electricity and water, choosing public transportation, and food-related behaviour. Specifically, the study found a correlation between access to sustainable tourism information and sustainable behaviour, including the choice of transportation (sig = 0.040) and food-related behaviour (sig = 0.006). Surprisingly, the study did not find a correlation between access to sustainable tourism information and behaviour related to conserving electricity and water at destination accommodations. The findings also revealed that well-educated young Vietnamese travellers (aged 18-35) earning high salaries, living in urban areas, and currently employed by international companies have a better understanding of sustainability, leading to increased sustainable practices within the tourism industry. Finally, the study suggests that strategies should shift towards changing behaviour related to saving electricity and water through improvements in hotel infrastructure and management practices rather than focusing solely on engaging sustainable tourist behaviour through providing sustainable information.