Kindle Fire HD tablets ordered online were on their way to buyers and more would be available at US consumer electronics shops beginning Friday, according to Amazon.
"Kindle Fire HD has been Amazon's best-selling product worldwide since launch, and that was before we even started shipping the best tablet we've ever built," said Kindle vice president Dave Limp.
"We think customers are going to love web browsing, email, gaming, watching TV shows, reading magazines, and more on the large, stunning HD screen, with fast Wi-Fi and exceptional audio."
Amazon in September unveiled the new Kindle Fire HD priced at $299 in what analysts saw as a clear challenge to the market-leading iPad.
The new Kindle Fire HD has an 8.9-inch (22.6-centimeter) display and was described by Amazon founder and chief executive Jeff Bezos as "the best high-end tablet anywhere, at any price" when combined with Amazon content and services.
The tablet is only 0.3 inches thick, and weighs 20 ounces (567 grams). The Kindle Fire HD has dual-band Wi-Fi and two antennas.
A seven-inch Kindle Fire HD priced at $199 became available in September.
In an even more direct challenge to the iPad, a 4G version of the larger Kindle Fire HD will sell at $499 - the same price as a basic iPad.
Amazon said that 4G Kindle Fire HD tablets will begin shipping next week.
Offering the Kindle Fire outside the US for the first time, all except the new bigger-screen version went on sale in Europe in October.
Apple early this month released a smaller version of its iPad to take on Amazon and Android tablets having success in that segment of the market.