Goodreads is the leading website for sharing book recommendations and would complement reader reviews provided at Amazon.com's online shop for digital titles.
"Goodreads has helped change how we discover and discuss books," said Amazon vice president Russ Grandinetti.
"Together we intend to build many new ways to delight readers and authors alike."
Since launching in early 2007, Goodreads has grown to boast more than 16 million members and 30,000 book clubs.
"It's important to be clear that Goodreads and the awesome team behind it are not going away," co-founder Otis Chandler said in a message posted at the Goodreads website.
"We remain a home for all types of readers, no matter if you read on paper, audio, digitally, from scrolls, or even stone tablets."
Features at Goodreads include tracking books read, discovering new titles, and connecting directly with authors.
Goodreads will remain in San Francisco, according to Amazon.com, which has its headquarters in Seattle. Financial terms were not disclosed.
Synching a vibrant online community of readers with Kindle tablets and Amazon's content promised to strengthen the company's position against e-book shops run by rivals such as Apple and Google.
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