Electronic book sales pass print.
The firm, which started selling the downloadable books in the UK in August 2010, said this year it has sold 114 Kindle titles for every 100 print books.
That includes both hardback and paperback but does not include Kindle titles that are available for free.
"Customers in the UK are now choosing Kindle books more often than print books, even as our print business continues to grow. We hit this milestone in the United States less than four years after introducing Kindle, so to reach this landmark after just two years in the UK is remarkable and shows how quickly UK readers are embracing Kindle," said Jorrit Van der Meulen, vice president of Kindle EU.