Vegetarian diets have gained in popularity worldwide and therefore an increasing number of children may be exposed to the resulting nutritional consequences. Among them, the risk of micronutrient shortfall is particularly of concern. This narrative review aims to assess and discuss the relevance of micronutrient deficiency risk based on the available data. It mainly draws attention to iron, zinc, iodine, and vitamins B12 and D intake. Diets that are more restrictive in animal source foods, such as vegan diets, have a greater likelihood of nutritional deficiencies. However, the actual risk of micronutrient deficiency in vegetarian children is relatively difficult to assert based on the limitations of evidence due to the lack of well-designed studies. The risk of vitamin B12 deficiency must be considered in newborns from vegan or macrobiotic mothers and children with the most restrictive diet, as well as the risk of iron, zinc, and iodine deficiency, possibly by performing the appropriate tests. A lacto-ovo-vegetarian diet exposes a low risk if it uses a very varied diet with a sufficient intake of dairy products. Vegan and macrobiotic diets should be avoided during pregnancy and childhood. There is a need for education and nutrition guidance and the need for supplementation should be assessed individually.