This study articulates the concepts of sustainability and work safety to understand how safe working practices enable knowledge in the practice of sustainability. Anchored in the lenses of the learning process of practiced-based studies, we conducted a case study of qualitative nature in a forest harvest operation of a Brazilian company with sustainability in the core of its business strategy. We adopted as collection tools in-depth observation, semi-structured interview, and documental research, which were assessed by the thematic analysis of narratives. As results, we identified that the learning process of sustainability occurs in this context in a combination of institutional mechanisms and practices located at the occupational communities. Among those, the safe working practices indicate being capable of enabling the knowledge in practice of the systemic and integrative perspective, carefulness, responsibility, and look to the future, reflecting the assumptions contained in the ideal of sustainability. We also verified that, with the practices, this group has been establishing alliances, building common concepts, and producing and reproducing practices that change the way of learning sustainability.