The United Nations plays an important role in supporting governments to implement nutrition policies and accelerate progress. The development of a common UN nutrition agenda and joint programming are two crucial aspects to improve complementarities and synergies to maximize the nutritional impact. The objective was to identify the success factors and challenges during the planning process of the UN common nutrition agenda in three different contexts. This is a qualitative study, conducted in Burkina Faso, Mali and Senegal between 2016 and 2018. The data was collected using an orientation kit developed by the UN Network which includes an inventory of UN nutrition actions, individual interviews, and consensus workshops. A total of 32 nutrition focal points from UN agencies participated in the study. In all countries, UN nutrition interventions were concentrated in areas with the highest number of stunted. Most of these actions were aligned with the priorities of nutrition policies and were complementary. Governance actions were mainly oriented towards sector governance. Key success of joint nutrition programming by UN includes commitment of country director and technicians, functional UN Network, participation of field-level stakeholders and strengthening of information between UN agencies. Certain prerequisites such as the existence of nutrition policy, stakeholder and action mapping, inventory of UN nutrition actions, situation analysis contributed to the formulation of a common nutrition agenda at country level. Among the challenges, we note effective implementation of joint programs to strengthen complementarity; diversity of beneficiary targeting strategies between sectors; low mobilization of resources; lack of coordination intra and inter agencies; understaffing; strengthening partnership and multisectoral accountability; ownership of the common nutrition agenda by all agencies. The development of common nutrition agenda and joint programs would maximize the nutritional impact in the country level.