When Chunli Fu, of Qingdao, China, downloaded Disney's puzzle game Where's My Water?, she triggered the completion of Apple's 'App Store Countdown to 25 Billion Apps'.
Since it launched in 2008, more than 25 billion apps have been downloaded from the App Store by users of around 315m iPhone, iPad and iPod Touch devices worldwide.
"We'd like to thank our customers and developers for helping us achieve this historic milestone of 25 billion apps downloaded," said Eddy Cue, Apple's senior vice president of internet software and services.
"When we launched the App Store less than four years ago, we never imagined that mobile apps would become the phenomenon they have, or that developers would create such an incredible selection of apps for iOS users."
The App Store has more than 550,000 different apps for Apple mobile devices across 21 different categories, including sport, news, travel and games. The store now has more than 170,000 native apps for the iPad, the tablet computer which was launched in 2010.
Apple claims that the App Store has paid out in excess of $4 billion (£2.5bn) to developers since it launched, along with making a hefty return for Apple itself, as the firm takes a 30% cut of the revenue.
> Top iPhone apps: The Simpsons, Evi, Lego
It is perhaps fitting that the 25 billionth app was downloaded in China, as the country is a key emerging market for Apple as it seeks to maintain its position as the world's second most valuable company.
However, the US firm is currently battling a ban on sales of its iPad tablet in China, as part of an increasingly bitter battle over the trademark with Proview Technologies.