Multivitamins are commonly used by the general population, often without medical prescription. The purpose of this report is to inform on the daily vitamin D supply provided by multivitamins containing vitamin D that are commercialized online by Amazon in Western and Southern Europe. We surveyed multivitamins aimed at adults using the following marketplaces: amazon.es®, amazon.de®, amazon.it®, and amazon.fr®. We identified 199 vitamin D3-containing multivitamins sold by Amazon marketplaces: 77 from amazon.es®, 73 from amazon.de®, 33 from amazon.it®, and 16 from amazon.fr®. No multivitamin contained vitamin D2. The daily vitamin D3 supply ranged from 16 to 2000 IU: it was less than 400 IU daily in 108 (54%), 400–800 IU daily in 53 (27%), and more than 800 IU daily in the remaining 38 (19%) products. The vitamin D3 supply of products sold by amazon.it® was on average higher (p < 0.05) than that of products sold by amazon.de®, amazon.fr®, and amazon.es®. In conclusion, the vitamin D supply of multivitamins sold by Amazon may be insufficient, marginally sufficient, or adequate for subjects at high risk of hypovitaminosis D such as subjects 65 years or more of age, pregnant (or lactating) women, or patients on drug treatment or with an underlying disease, where a vitamin D supplementation is advocated.