Abstract Background Over the past decades, the survival rate for childhood cancer has greatly improved. However, the risk of late cardiac complications after cancer treatment remains high. Previous studies have shown that the risk for heart failure among childhood cancer survivors is significantly higher than that observed in varying control populations. The aim of this systematic review is to identify, critically appraise, and synthesize existing population-based studies reporting on the frequency of heart failure, both the incidence and prevalence, that may develop after treatment for childhood cancer. Method The following databases will be searched from their inception date until May 17, 2021: MEDLINE, Embase, Scopus, CINAHL, CAB International, AMED, Global Health, PsycINFO, Web of Science, and Google Scholar. Population-based studies reporting on the incidence and/or prevalence of heart failure after the treatment of any type of childhood cancer will be included. The screening of articles, data extraction, and quality assessment will be performed independently by two reviewers. The quality and risk of bias in the included studies will be assessed by using the Effective Public Health Practice Project tool. A narrative synthesis of the extracted data will be carried out, and for studies that are sufficiently homogenous, a meta-analysis using random-effects models will be performed. Discussion This systematic review will provide a clearer picture of the epidemiology of heart failure after the treatment of childhood cancer. The collected data will be of value for future childhood cancer treatment protocols and will offer guidance for posttreatment cardiac surveillance among survivors. Systematic review registration PROSPERO CRD42021247622. Registered on April 28, 2021. This protocol follows the structure of the recommendation of the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P).