Background The burden of cardiovascular diseases (CVDs) greatly varies between and within countries. Low- and middle-income countries (LMICs) and vulnerable communities of high-income countries (HIC) share disproportionately higher burden. Evidence is limited on the level of CVD knowledge and risk perception in vulnerable communities. Hence, in this study, we assessed the level of CVD knowledge, risk perception and change intention towards physical activity and healthy diet among vulnerable communities in Antwerp, Belgium and Nottingham, England. Furthermore, we investigated the socioeconomic disparities particularly in the Antwerp setting. Method A cross-sectional study was performed among 1,424 adults (958 in Antwerp and 466 in Nottingham) aged 18 or older among selected vulnerable communities. Districts or counties were selected based on socioeconomic and multiple deprivation index. A stratified random sampling was used in Antwerp, and purposive sampling in Nottingham. We determined the level of CVD knowledge, risk perception and intention towards a healthy lifestyle in Antwerp and Nottingham using a percentage score out of 100. To identify independent socioeconomic determinants in CVD knowledge, risk perception, intention to PA and healthy diet, we performed multilevel multivariable modeling using the Antwerp dataset. Results The mean knowledge percent score was 75.4 in Antwerp and 69.4 in Nottingham, and only 36.5% and 21.1% of participants respectively, had good CVD knowledge (scored 80% or above). In the multivariable analysis using the Antwerp dataset, level of education was significantly associated with (1) CVD knowledge score (Adjusted beta = 0.11, 95%CI: 0.03, 0.18), (2) risk perception (0.23, 95%CI: 0.04, 0.41), (3) intention to physical activity (PA) (0.51, 95%CI: 0.35, 0.66), and (4) healthy diet intention (0.54, 95%CI: 0.32, 0.75). Furthermore, those individuals with a higher household income had a better healthy diet intention (0.44, 95%CI: 0.23, 0.65). In contrast, those who were of non-European ...