Background: The Mediterranean diet is considered a healthy dietary pattern associated with substantial health benefits. While its application at global level is rather difficult due to the intricate features eradicated into the cultural heritage of populations living in countries facing the Mediterranean basin, its preservation in such areas is considered crucial to maintain a good health status of current and future generations. Objective: To assess the level of adherence to the Mediterranean diet in children and adolescents living in 5 Mediterranean countries participating in the DELICIOUS project. Methods: An online survey was conducted involving 2011 parents of children and adolescents from Spain, Italy, Lebanon, Egypt, and Portugal. The KIDMED score applied to 24-h recalls of their children's diets was used to assess the level of adherence to the Mediterranean diet and cross-references with background and lifestyle variables. Results: Children and adolescents living in Lebanon and Portugal are more adherent than their counterparts in other countries. Some specific aspects related to the Mediterranean diet were rather common, such as olive oil consumption, daily fruit and vegetable intake, as well as lifestyle habits including having breakfast and limited sweets. Others, including having a second portion of fruit and vegetable, adequate consumption of fish, nuts, and cereals (for breakfast), as well as frequent consumption of fast foods underscored substantial abandonment of certain other Mediterranean diet features. Older adolescents with inadequate sleep duration, longer screen time, and low physical activity levels, as well as children of older parents with lower educational level, lower family income, and living in rural areas had significantly lower KIDMED scores. Conclusions: This study provides important information on the current status of adherence to the Mediterranean among children and adolescents in the Mediterranean region and may help setting specific targets for nutrition interventions aiming at its promotion.