This is the third round of investments from the German firm, which has already invested £9 million in he online wine retailer set up by Rowan Gormley in 2008.
Naked Wines now supplies around 10 million bottles of wine to 150,000 customers, and a third of them are in the US and Australia.
Customers are called “angels”, who invest £20 per month in winemakers and in return receive discounts and access to any wine produced.
With the increased investment Gormley believes the number of angels will soon rise to 250,000.
In 2012 Naked Wines turned its first profit – of £1 million – and it said revenues have since increased 57% year-on-year.