Various forms of malnutrition, including hunger, micronutrient deficiencies and non-communicable diseases caused by unbalanced nutrition, threaten food security in Africa. The project HealthyDiest4Africa is based on the central hypothesis that diversification of the food system helps to combat all forms of malnutrition while minimizing its environmental footprint. To this aim, we will monitor dietary diversity in eight African countries representing different regions, and develop target group-specific metrics to measure the diversity of the food system and its health outcomes. A production-oriented cluster of the project will explore environmentally sustainable options to diversity food production that specifically address the nutritional requirements identified for the target populations. This includes the development of novel and biofortified crop varieties, utilization of orphan crops with high nutritional value, and diversification of cropping systems and food processing technology. We will link these efforts with a consumption-oriented cluster exploring the consumer acceptance, food safety, and nutritional health effects of diet diversification options. The best solutions that contribute to healthy diets via diversification while also promoting environmental health will be up-scaled via a network of food system stakeholders in eight African countries. HealthyDiets4Africa will also devise communication and policy strategies to maximize outreach and impact of diversified food systems. Thereby the project will help to develop safe, healthy and affordable diets by adopting a diversification strategy that will simultaneously reduce the pressure of food production on the environment.