Sustainable fashion apparel is a recent movement within the fashion industry that aims to reduce textile waste and environmental depletion while increasing ethical treatment of workers; the goal is to slow down the global production and consumption process in order to form an industry that will be more sustainable in the long run. Along with the development of more socially and eco-conscious production and marketing practices, there is still room for the sustainable fashion movement to grow beyond its current scope in Sri Lankan context. The purpose of this study is to understand consumer awareness and factors influencing to consumer awareness toward sustainable fashion apparel in Sri Lanka. Among the different types of applications, with the help of past literature, study selected four independent variables (promotional strategies on sustainable fashion apparel, knowledge of sustainable fashion apparel, sociocultural factors of sustainable fashion apparel and cost of sustainable fashion apparel) which there could be a relationship to consumer awareness and hypotheses were formulated. This has been surveyed with a questionnaire in which 102 respondents in Colombo district between age of 25-29 participated, and obtained data were analyzed using IBM SPSS to investigate internal reliability, univariate analysis, bivariate analysis, regression analysis and hypotheses testing. Based on the conducted research, the researcher identified the positive impact from independent variables towards the dependent variable and based on the finding, recommendations were given.