The objective of this article is to describe characteristics of the cooperative sector and highlight the contributions of agricultural cooperatives in promoting sustainable and resilient food systems in Brazil, Guinea‐Bissau, Portugal, and São Tomé and Principe. Semi‐structured interviews were conducted with representatives of national organizations linked to cooperativism and leaders of agricultural cooperatives in the four countries. We found great discrepancies between the institutional and regulatory environments of cooperativism in Brazil and Portugal, which have institutionalized national systems of representation, regulation, and support for the sector, and São Tomé and Principe and Guinea‐Bissau, whose environments are fragile and insecure for cooperatives. However, despite the challenges, the cases of cooperatives analyzed show how these organizations are fundamental to their members and their communities, offering technologies, social and cultural support, and technical services to their members and undertaking actions and projects to make agriculture more sustainable and productive. We conclude that the cooperative sector and cooperatives, especially those formed and run by family farmers, have taken on the role of sustainable development agents.