Informal commercialisation of agricultural products is widespread in Colombian food systems. It plays a central role in supporting rural livelihoods and affordable food access, but may limit value creation, create fiscal pressures, and undermine the evidence base for policymaking. This paper examines why small-scale farmers in Colombia rely on informal markets, with particular attention to Afro-Colombian and Indigenous communities. It situates informality within the broader context of rural areas and the structure of the agri-food supply chain. It proposes a characterisation of the main barriers that hinder small-scale farmers’ engagement with formal buyers, drawing on desk research and interviews with government officials, industry stakeholders, community representatives, and academics. It suggests that formal market participation could be facilitated by prioritising the provision of rural public goods, improving data and evidence on informality in food systems, better aligning agricultural policies with producer-financed parafiscal funds, and adopting a demand-driven approach to agricultural policy.