The positive impact of numerous healthy behaviours on human health and wellbeing is well known. This study is the first to provide a comprehensive single healthy lifestyle score for a heterogeneous adult population in Bulgaria. The aim of this study is to make single healthy lifestyle score of the adults in Bulgaria. The survey was carried out with 714 randomly selected participants. A relative lifestyle score (RLS) was based on smoking status, alcohol consumption, physical activity, diet and BMI of respondents. The RLS ranged from 0 to 5, and a higher score representing a healthier lifestyle. The relationship between respondents’ healthy behaviours and demographic features was determined via the Pearson correlation coefficient. We found that the healthy lifestyle score of the participants is 2.98 of 5.00. The relatively lifestyle score of halves (45.94%) of them is in the range of 3.9-4.29. Regarding smoking and alcohol consumption, respondents' behaviour is the healthiest: 63.31% nonsmokers and 68.63% abstainers. Low physical activity and mixed diet patterns are the main risk factors for optimal healthy lifestyle achievement. We identified the demographic groups that are most vulnerable. Our study provides a possibility for reliable comparisons of healthy lifestyle levels among populations across countries. The RLS is a reliable tool for assessment a healthy lifestyle both of individuals and the community.