The stock plummeted 14 percent to $194.31 after hours, after closing at $227.15 on Nasdaq.
The world's largest Internet retailer said on Tuesday its third-quarter net income was $63 million, or 14 cents a share, versus $231 million, or 51 cents a share, a year earlier. Revenue was $10.88 billion, up 44 percent from the third quarter of 2010, it added.
Analysts had expected Amazon to report third-quarter earnings per share of 24 cents on revenue of $10.95 billion, according to Thomson Reuters I/B/E/S.
"Lower profit margins would be acceptable, but for the lower-than-expected revenue growth numbers," said Fred Moran, an analyst at The Benchmark Co.
Moran had expected third-quarter revenue growth of as much as 50 percent.
(Reporting by Alistair Barr; Editing by Richard Chang)