AMAZON profits surged by 71 per cent in the final three months of 2009.
The online bookseller said its Kindle electronic book reader had driven the sales boom.
The device – Amazon's bestselling product – will face competition from Apple’s new iPad, which was unveiled this week.
Overall sales at Amazon – which now offers thousands of other products online – rose 42 per cent to £5.89bn.
Its pre-tax profit was £237m over the period.
Amazon founder Jeff Bezos said: "Millions of people now own Kindles, and Kindle owners read, a lot.
"When we have both editions, we sell six Kindle books for every 10 physical books.
"This is year-to-date and includes only paid books – free Kindle books would make the number even higher.
"It's been an exciting 27 months."
The Seattle-based firm said revenue from books, CDs, DVDs and other media generated £2.89bn while sales of electronics and other "general merchandise" brought in £2.85bn.
Amazon cut the price of the Kindle to £160 in an effort to fuel Christmas sales.