IntroductionGlobally, children are not meeting the recommended serves of the five food group foods, particularly vegetables. Childcare is an opportune setting to improve children’s diet quality. This study aims to assess the effectiveness of a menu box delivery service tailored to the long day care setting to improve menu compliance with recommendations and improve children’s food intake while in care.Methods and analysisThis study will employ a cluster randomised controlled trial and will recruit eight long day care centres, randomly allocated to the intervention or comparison groups. The intervention group will trial the delivery of a weekly menu box service that includes all ingredients and recipes required to provide morning snack, lunch and afternoon snack. The menu boxes are underpinned by a 4-week menu developed by dietitians and meet menu planning guidelines. The comparison group will receive access to online menu planning training and a menu assessment tool for cooks. The primary outcomes are child dietary intake and menu guideline compliance. Secondary outcomes include within-trial cost-effectiveness and process evaluation measures including intervention acceptability, usability and fidelity. If effective, the menu box delivery will provide an easy strategy for childcare cooks to implement a centre menu that meets menu planning guidelines and improves child intake of five food group foods, including vegetables.Ethics and disseminationThis study was approved by the Flinders University Social and Behavioural Research Ethics Committee. Study outcomes will be disseminated in peer-reviewed publications, via local, national and international presentations. Non-traditional outputs including evidence summaries and development of a business case will be used to disseminate study findings to relevant stakeholder groups. Data will be used in a doctoral thesis.Trial registration numberAustralian New Zealand Clinical Trials Registry (ACTRN12620000296932).