Purpose: The paper aims to identify the ecological orientations of the Swedish start-ups and explore the opportunities and challenges to determine their environmental sustainability actions. Methods: The study used a qualitative method for conducting this exploratory type of research. This paper focused mainly on primary data; semi-structured interviews were conducted on ten Swedish start-ups to explore their sustainable environmental practices. Finally, the collected data were analyzed through cross-case analyses. Findings: Firstly, the findings of the paper posit that the ten Swedish start-ups belong to eco-dedicated, eco-open and eco-reluctant orientations according to their business practices. Secondly, the study explores that saving cost for long run, reusability of components, and the best use of available resources are major opportunities whereas the prime challenges are the additional cost of eco-friendly solutions, customers' price sensitiveness and market competition. And thirdly, the study determines sustainability actions of three categories of start-ups that are self-motivated, hybrid and government support driven.  Contribution: This study contributes to the knowledge of environmental sustainability practices of Swedish start-ups through the lens of ecological orientation. The sole focus on environmental sustainability dimension enhances the theoretical understanding of the start-ups’ actions according to their ecological orientations. Further, this paper equips academic researchers with valuable information of Swedish start-ups’ environmental sustainability actions and help to determine the contribution of the start-ups in environmental sustainability continuum. Moreover, the findings inform about the benefits of environmentally sustainable practices for new businesses. The paper also provides multifaceted information to the business managers about the sustainability actions of start-ups as per their ecological orientations. Conclusions: The result of the study shows that eco-dedicated start-ups are proactive in case of pursuing the environmental sustainability actions while eco-open businesses incorporate both self-driven and regulatory actions. And the sustainability actions of eco-reluctant startups are dependent on the government supports and regulations.