The organisation reported gains of 188% in the sector for the first six months of the year when compared to the same period in 2011, according to BBC News.
Sales of children's e-books rose by 171%, while non-fiction titles increased by 128%. Physical book purchases saw a year-on-year decline of 0.4%, but combined sales of digital and print titles were up by 6.1%.
"Certainly the strong e-book growth has taken the tarnish off the otherwise tricky market," said Philip Jones, editor of The Bookseller.
"It is good news that the market is transitioning and making money from that, but it is moving to a trickier situation where there are fewer booksellers."
Combined sales of physical and digital books helped the market rake in revenue of £1.1 billion for the first half of the year, but Jones expressed concerns about the uncertainty of a business in transition.
"There's a good deal of uncertainty about what will happen on Boxing Day 2012 when a few million people open up their tablet and think, 'What am I going to buy on it?'"
Amazon's Kindle Fire HD, announced earlier this month, is expected to have a significant impact on the e-book market when it starts shipping in October.