INTRODUCTION: Approximately 250 million children under 5 years of age are at risk of poor development in low-income and middle-income countries. However, existing early childhood development (ECD) interventions can be expensive, labour intensive and challenging to deliver at scale. Mass media may offer an alternative approach to ECD intervention. This protocol describes the planned economic evaluation of a cluster-randomised controlled trial of a radio campaign promoting responsive caregiving and opportunities for early learning during the first 3 years of life in rural Burkina Faso (SUNRISE trial). METHODS AND ANALYSIS: The economic evaluation of the SUNRISE trial will be conducted as a within-trial analysis from the provider's perspective. Incremental costs and health outcomes of the radio campaign will be compared with standard broadcasting (ie, 'do nothing' comparator). All costs associated with creating and broadcasting the radio campaign during intervention start-up and implementation will be captured. The cost per child under 3 years old reached by the intervention will be calculated. Incremental cost-effectiveness ratios will be calculated for the trial's primary outcome (ie, incremental cost per SD of cognitive gain). A cost-consequence analysis will also be presented, whereby all relevant costs and outcomes are tabulated. Finally, an analysis will be conducted to assess the equity impact of the intervention. ETHICS AND DISSEMINATION: The SUNRISE trial has ethical approval from the ethics committees of the Ministry of Health, Burkina Faso, University College London and the London School of Hygiene and Tropical Medicine. The results of the economic evaluation will be disseminated in a peer-reviewed journal and presented at a relevant international conference. TRIAL REGISTRATION NUMBER: The SUNRISE trial was registered with ClinicalTrials.gov on 19 April 2019 (identifier: NCT05335395).