New firms face challenges regarding pace, time, scalability, and societal changes, requiring increased attention to sustainable work prerequisites. However, this dimension of social sustainability is less studied than economic and ecological sustainability. This paper addresses how sustainable work is considered in an entrepreneurial startup carrying out a greenfield project within a new industrial domain. Data were collected for 30 months in a longitudinal case study. The study shows that (i) working condition challenges were drivers for innovative solution-oriented approaches with potential for rapid decision-making, flexibility, and to attract, recruit, retain, and develop talented people; (ii) a strategic focus on sustainability and collective contribution to a purpose-driven vision were important enablers for taking steps of operationalising sustainable work dimensions during the startup; and (iii) the firm’s early stakeholder collaboration addressing working conditions was an important means for design for sustainable work and their role as agents of sustainable work. Research implications are how sustainable work can be considered during startups and through stakeholder collaboration. Furthermore, the case contributes to increased knowledge of how the three pillars of sustainability—economic, ecological, and social sustainability—are interrelated and are suggested to be continuously considered over time, specifically during rapid major changes.