External stakeholder collaboration is vital for new industrial projects and establishments. The aim of this paper is to explore why and how new firms can create relations and stakeholder collaboration with trade unions during industrial start-ups. A case study was carried out in the early phases of a new firm´s major greenfield project aimed at establishing a new industrial domain in a Nordic context. The results showed that early co-operation between a new firm and trade unions has the potential to proactively address prerequisites for sustainable work in design phases of new factories, but also to strengthen the attention to other dimensions of social sustainability that are crucial for an industrial start-up’s longterm possibilities for success. However, specifically in a rapidly growing new firm, there needs to be a systematic approach that incorporates continuous anchoring activities both within and between the stakeholders. Practical implications are how new firms can initiate and establish co-operation with trade unions and other social partners in fast-moving work environments and change processes. Hence, the study identifies advantages and approaches for new firms to build relations  with trade unions in a stakeholder collaboration chain inspired by the Nordic model. Further, to proactively pay attention to dimensions of social sustainability in a new firm´s early development phases and change processes, such as industrial start-ups, seems beneficial from an individual, business, and a societal perspective.