Background: The World Health Organization has identified four major behavioural risk factors—tobacco use, excessive alcohol consumption, an unhealthy diet and physical inactivity—that substantially contribute to non-communicable diseases and can increase the risk of death. A literature review revealed that clustering patterns of multiple health-risk behaviours among the Chinese population have been underexplored. This study investigated the prevalence and clustering patterns of multiple health-risk behaviours and their associations with non-communicable diseases among Chinese adults in Hong Kong.Methods: A large sample survey was conducted in all 18 districts of Hong Kong between 21 June and 31 August 2021. A behavioural health-risk factor survey was used to collect demographic data and information regarding smoking, alcohol consumption, physical inactivity and an unhealthy diet.Results: A total of 5,737 adults completed the survey. Overall, 4,605 (80.3%) had at least one health-risk behaviour, and 2,696 (47.0%) had two or more health-risk behaviours. Multiple health-risk behaviours were more prevalent among men. The prevalence of smoking and alcohol consumption among Hong Kong Chinese women was considerably lower than in most Western countries. In contrast to previous findings, this study revealed that a high proportion of adults with high educational attainment or household income had multiple health-risk behaviours. In addition, this study revealed that the health-risk behaviours in Chinese adults co-occurred in clusters, with smoking and alcohol consumption co-occurring with other health-risk behaviours. Those who smoked or consumed alcohol had the highest proportion of multiple health-risk behaviours and the highest proportion of non-communicable diseases.Conclusion: This study addressed the gaps in the literature by examining the clustering patterns of multiple health-risk behaviours among Hong Kong Chinese adults. The findings add further evidence that health-risk behaviours co-occur in clusters and can contribute to non-communicable diseases.Trial registration: Registered at clinicaltrials.org (NCT04961073) on 14/07/2021.