Objectives: To investigate the association of participation in arts and cultural activities with health behaviours and mental well-being in low-income populations in London. Study design: Cross-sectional, community-based observational study. Methods: Data were taken from the cross-sectional baseline survey of the Well London cluster randomized trial, conducted during 2008 in 40 of the most deprived census lower super output areas in London (selected using the English Indices of Multiple Deprivation). Multiple imputation was used to account for missing data in the Well London survey. Descriptive statistics and regression analyses were used to examine the association between participation in arts and cultural activities and physical activity (meeting target of five sessions of at least 30 min of moderate-intensity physical activity per week), healthy eating (meeting target of at least five portions of fruit or vegetables per day) and mental well-being (Hope Scale score; feeling anxious or depressed). Results: This study found that levels of arts and cultural engagement in low-income groups in London are >75%, but this is well below the national average for England. Individuals who were more socially disadvantaged (unemployed, living in rented social housing, low educational attainment, low disposable income) were less likely to participate in arts or cultural activities. Arts participation was strongly associated with healthy eating, physical activity and positive mental well-being, with no evidence of confounding by socioeconomic or sociodemographic factors. Neither positive mental well-being nor social capital appeared to mediate the relationship between arts participation and health behaviours. Conclusion: This study suggests that arts and cultural activities are independently associated with health behaviours and mental well-being. Further qualitative and prospective intervention studies are needed to elucidate the nature of the relationship between health behaviours, mental well-being and arts participation. If arts activities are to be recommended for health improvement, social inequalities in access to arts and cultural activities must be addressed in order to prevent further reinforcement of health inequalities.