We cost-effectively increase smallholder farmers’ access to and uptake of critical agricultural and nutrition information by partnering with existing extension providers to produce short videos featuring local farmers demonstrating improved practices. Peer community members and extension agents screen the videos among farmer groups and women-led self-help groups, facilitate interactive discussions and gather feedback, and subsequently visit viewers’ fields and homes to observe uptake of promoted practices. We have facilitated production of more than 6,000 localized videos in 50 languages and dialects, which have been screened by 17,000 frontline workers to reach 2.3 million rural households (77% women) in South Asia and Sub-Saharan Africa. More than 50% of viewers have adopted at least one practice (3 to 4 on average), representing 3.5 million total adoptions. More than a message delivery vehicle, our approach has organized timely knowledge exchange, and strengthened the social structures that meet to discuss them. Integration of data and feedback has given farmers a voice, increased their production and incomes, and helped national extension systems better respond to community needs. Evaluations have shown that the approach increases the reach, effectiveness and cost-effectiveness of extension providers, and the engagement of extension staff. By prioritizing promotion of practices with highest return on investment, we are increasing farmers’ yields and incomes.