Work, family and social life are considered to be the most important spheres for an individual’s life. The current study focuses on to determine the level of work-life balance, to analyze the impacts of perceived role demands on work-life balance and to estimate the moderating effects of work ethics between role demands and work-life balance relationship among professionals in Sri Lanka. The sample consists of 386 professionals of Chartered Engineers, Medical Officers and Accountants employed in the public sector organizations in Sri Lanka. Explanatory research design with quantitative research approach of cross sectional survey method was adapted. Primary data was collected using Questionnaire survey with stratified random sampling techniques. Data were analyzed using Structural Equation Modelling approach with Amos 21 and SPSS statistics 23. The Multi-Group Analysis in Amos also has been applied for testing the moderation effect of work ethics. This study found that professionals possess a moderate level of work-life balance and there is significant and negative causal impacts of perceived work and social demands on work-life balance while combined effects of perceived role demands have significantly and negatively impact on work - life balance. Moreover, work-life balance is skewed towards works and less in family and social role demand is an emerging issue for professionals. Further, work ethic has significant and partial moderation effect between role demands and work-life balance relationships. This study is significant and beneficial for managers, organizational leaders and researchers to address the needs of employees to develop strategies and policies to address work - life balance issues and social implications for employees, family members, societies and researchers. The limitation of the study is that all of the measures were self-reported that common method variance may raise concern. Future studies using longitudinal design would be useful in establishing the temporal causal relationship among the private sector professionals in Sri Lanka.