The fashion industry has faced a radical change in how the market has been operating towards a more digitized landscape, and several fashion brands have started developing greater customer experiences as well as engaging the consumers with conveyance of authentic content. Since fashion collaborations can increase awareness and have an immense impact on the consumers’ perception, the concept of creating sustainable collaborations have become an ideal way to meet the needs of the millennial consumers. The topic of sustainable fashion collaborations has started to emerge and the way it is perceived by consumers appears to be unstudied, which makes it very fascinating to analyse. The purpose of this study is to investigate consumers’ response towards sustainable fashion collaborations and how these co-branding projects are marketed to and perceived by millennials. On the basis of this purpose, the following research questions have been formulated: How are sustainable fashion collaborations communicated in the consumers’ eyes? How is the response of millennial consumers towards sustainable fashion collaborations? This study was conducted with an abductive approach, and data was obtained from literature and interviews. A qualitative method was applied, with the definition of four case studies to analyse through semi-structured interviews conducted with twelve millennial consumers. Messages and campaigns can not be superficially developed and need to be explanatory to the eyes of consumers, in order to avoid greenwashing and generating the need to fill in communication gaps. In this sense, storytelling also resulted to be a positive addition to the communication of sustainable fashion collaborations, creating an emotional connection with consumers. Since positive sustainable associations to a brand can only be developed through recognition, this aspect is also fundamental when communicating sustainable products. Moreover, millennial consumers require brands to have a balanced communication in terms of sustainability and fashion content, even when it comes to sustainable fashion collaborations. To conclude, it can be said that millennial consumers are definitely drawn to social media communication, but if brands want to reach a wider audience with their products and sustainability efforts, millennials themselves suggest the use of other communication channels. This study can, in the long-term, contribute to the knowledge and strategies of fashion companies and understanding the needs and expectations of consumers towards the communication of current matters like sustainability.