In contrast, Carrefour came in second place with 6.3 million Facebook fans. Tesco was third with 4.4 million.
Lidl UK launched on Facebook in March 2011 and grew its fanbase to 250,000 in January 2013, doubling to half a million by the end of November 2013.
The supermarket’s UK Facebook page now has more than 600,000 fans and its following has been boosted by activity including its recent Easter Rally, which gave players the chance to win £50 Lidl vouchers.
Its social media growth coincides with it and fellow discounter Aldi stealing market share off the big four supermarkets, according to data from Kantar.
Lidl now has 26 Facebook pages across Europe and a fan community of 10.2 million followers with an average penetration rate of around 5.9% within the European countries it has a Facebook presence.
Andreas Brückner, managing director of social media agency MRM Worldwide, said: "Lidl uses Facebook to communicate with its customers openly and transparently through dialogue [and] actively encourages its followers to become involved.
"Products have already been jointly developed with the communities (crowd sourcing) and fundraising campaigns carried out [through crowd funding].
"In a few countries, the followers have been able to decide which products from the Lidl range should go on special offer in store."