Andrea Zucchiatti took the photo of Berlusconi as he perused the fast food chain's menu, before sharing the snapshot with the football fan Facebook page Calciatori Brutti. In less than 24 hours, it has been 'liked' almost 45,000 times and attracted thousands of Idea.
"He's learned from Breaking Bad - you close the best deals at fast food restaurants," joked one commenter, while some wondered if his appearance at the chain was a sign that his sale of AC Milan to Chinese buyers had fallen through.
Others remarked on the fact that the ex-PM appeared to be receiving table service at the restaurant.
The so-called 'Cavaliere' is no stranger to social media fame, however. When Berlusconi was ousted from the Italian parliament in 2013, the event attracted a record number of Facebook and Twitter posts.
McDonald's in Italy
Along with other foreign fast food chains, McDonald's has a problematic history in Italy.