The social determinants of health affect an individual's capacity to cope during a crisis such as the COVID-19 pandemic which could potentially impact their well-being. The aim of this study was to examine the relationship between well-being and the social determinants of health among Australian adults during the COVID-19 pandemic. A cross-sectional study of adults residing in Australia was conducted using SurveyMonkey between 20 August and 14 October 2020. Participants were recruited via social media. Well-being was measured using the 10-item Multicultural Quality of Life Index and social determinants of health were measured using validated tools and investigator developed questions. Data were analysed using SPSS version 25. Inferential statistics, including independent t-test and one-way ANOVA, were undertaken. Multiple regression analysis was used to investigate the predictors of well-being. In total, 1211 responses were received. Females accounted for 80.7% of the responses, men 16.7% and transgender/non-binary 2.6%. The mean age of the respondents was 43 years (SD 14.2). The mean score for total well-being was 62.58 (SD 21.22). The significant predictors of higher well-being were housing security (p��=��0.000), food security (p��=��0.000), social support (p��=��0.000) and access to healthcare (p��=��0.000). This study demonstrates that those with poor social support, difficulty accessing healthcare, insecure housing and food insecurity had significantly poorer well-being during the COVID-19 pandemic. It shows that the COVID-19 pandemic has exacerbated social vulnerabilities and highlights the need for action to address the social determinants of health and inequalities.