Commercial cereals are among the first complementary foods fed to infants in Germany and elsewhere. The purpose of this national survey is to describe the nutritional adequacy of commercial complementary cereals. A comprehensive, cross-sectional survey of cereal manufacturer websites (n = 15) was conducted from March to April 2019. Food labels were analyzed for iron, zinc, iodine, sodium, and sugar contents in commercial complementary cereals, and ingredient lists were evaluated for whole grains and added sugars. Preparation instructions were evaluated for the type of liquid recommended for reconstitution. Among 164 commercial complementary cereals, few contain iron (n = 43, 26%), zinc (n = 23, 14%) or iodine (n = 43, 26%). Sodium contents fall within EU thresholds. Most cereals were single grain, containing only wheat (n = 54), with half of the products (n = 86, 52%) containing whole grains. The average carbohydrate content of dry cereals is 69 g/100 g ± 9 g of which 14 ± 15 g is sugar. Preparation instructions for breakfast porridges and cereals recommend formula or toddler milk, while few recommend human milk (n = 13, 18%). Few commercial complementary cereals contain appreciable amounts (at least 15% of daily reference values) of zinc, iron, or iodine. A quarter of cereal carbohydrates are sugar and one-third of the products contain added sugars. Future directives should stipulate minimum micronutrient levels, strictly regulate sugar contents, and include human milk among preparation instructions.