Cocoa is globally the third agricultural commodity traded in terms of value. The cocoa world production is relatively stable since 2010, amounting to around 4.5 million tonnes. Eight countries account for 90 % of the cocoa production, of which four West African countries. Under traditional cultivation practices, cocoa yields are poor with an average of ten fruits per cacao (Theobroma cacao L.), even though it has a potential to yield more than 100 fruits. As for most tree crops, the yields are depending on many factors, of which the more important are planting material, climate, cultural practices, and soil. Cacao is cultivated on many types of soil, and in various conditions, from agroforestry systems to full sun. Soil degradation and low soil fertility are among the main causes of low cocoa productivity. However, despite this inherent low fertility, most of the cocoa farmers do not use fertilizer because they are not well informed of the agricultural and fertilizers issues. Here we first review why fertilizers are used and how to optimize their effects, particularly farming practices and soil fertility management in full sun or shaded plantations. Secondly, we describe soil diagnosis and the foliar diagnosis, the two complementary approaches that were developed to assess the nutritional needs of cacao. The soil diagnosis provides a means to improve soil nutrient availabilities, while foliar diagnosis provides information on the cacao health. Third, we review the methods used to design fertilizer formulae and doses, and how they are calculated. Fertilizer inputs and mode of application are determined from the local conditions and farming practices. Finally, we review the effects of nutrients on the characteristics of the cocoa tree and cacao product. Finally, some current issues are discussed, such as the use of advising a single formula for a whole region or country and how to develop adoption of fertilizer by cocoa farmers.