This study aims to assess the impact of green brand positioning, consumers’ attitudes toward green brands, and green brand knowledge on green product purchase intention among people in Colombo City Limit in Sri Lanka. A standard questionnaire was used to gather the data from 200 consumers, and the purposive sampling technique was used to collect the data. The survey was carried out in reputed supermarket chain in Sri Lanka. Three hypotheses were developed for this research, and all hypotheses were tested using Pearson correlation analysis, multiple regression analysis, and descriptive statistics. The coefficient values of green product positioning, attitude, and knowledge positively correlate to consumers’ purchase intention, which means that independent variables such as green product positioning, green brand attitude, and green brand knowledge are the strongest predictors of determining green product purchase intention among consumers. Thus, based on our findings, we recommend that green brand positioning be used as a marketing strategy to improve green brand knowledge and attitudes, encourage consumers to demand more goods, and increase business sales and revenue. Moreover, it can be used to differentiate their products from the available competitors by giving the influence that their products are unique. In addition, the government can encourage businesses to invest in environmentally friendly products by granting financial or non-financial benefits.