Sales in stores began on Friday in Japan, Australia, France, the UK, Germany, Canada and the United States.
The company took more than 1 million online orders in the first 24 hours after the release of the iPhone 4S, exceeding the 600,000 for the iPhone 4, though it was sold in fewer countries.
Unveiled just a day before Apple Chairman Steve Jobs died, it was initially dubbed a disappointment, partly because it looked identical to its predecessor. But anticipation of its "Siri" voice software helped it set an online record in orders on Oct. 7.
Along with the new iPhone, more than 25 million customers are using the iOS 5 mobile operating system, in the first five days of its release, and more than 20 million customers have signed up for its free cloud services, Apple said.
The latest iPhone will be available in 22 more countries on Oct. 28 and more than 70 countries by the end of the year.