Background With the worldwide levels of obesity new venues for promotion of healthy eating habits are necessary. Considering children's eating habits are founded during their preschool years early educational establishments are a promising place for making health promoting interventions. Methods This systematic review evaluates different types of healthy eating interventions attempting to prevent obesity among 3 to 6 year-olds in preschools, kindergartens and day care facilities. Studies that included single interventions, educational interventions and/or multicomponent interventions were eligible for review. Included studies also had to have conducted both baseline and follow-up measurements. A systematic search of the databases Scopus, Web of Science, CINAHL and PubMed was conducted to identify articles that met the inclusion criteria. The bibliographies of identified articles were also searched for relevant articles. Results The review identified 4186 articles, of which 26 studies met the inclusion criteria. Fifteen of the interventions took place in preschools, 10 in kindergartens and 1 in another facility where children were cared for by individuals other than their parents. Seventeen of the 26 included studies were located in North America, 1 in South America f in Asia, and 3 in a European context. Healthy eating interventions in day care facilities increased fruit and vegetable consumption and nutrition related knowledge among the target groups. Only 2 studies reported a significant decrease in body mass index. Conclusions This review highlights the scarcity of properly designed healthy eating interventions using clear indicators and verifiable outcomes. The potential of preschools as a potential setting for influencing children's food choice at an early age should be more widely recognised and utilised.