Launched in May 2009, the free App delivers breaking news stories via text, images and video across six different categories - top stories, UK news, sport, business, world news and showbiz.
The App passed 1m downloads at the start of January and has consistently appeared at the top of Apple's free download charts for the UK and Ireland.
Buoyed by the success, Sky News has also launched a new mobile internet service to bring its breaking news stories to a range of other smartphones.
Available free of charge from a dedicated Sky News Web Mobile internet site, the service is tailored to the sophistication of each mobile device, ranging from just text-based news to rich video content.
However, the actual news content will be "exactly the same across all levels of the service" and broadly similar to that already offered on the iPhone App.
"In less than a year we've already seen millions of downloads of Sky's various iPhone apps and the Sky News has been an important factor in this" said Sky general manager for mobile David Gibbs.
"Now, by launching our mobile internet service beginning with Sky News, we are able to provide a tailored experience to the increasing number of customers looking to access Sky News via their mobile."
Sky News executive producer for new media James Weeks added: "The feedback for our iPhone app has been overwhelmingly positive since day one, and we're delighted that it has reached the magic million download mark.
"And the launch of the new mobile web service for users of non-iPhone mobile devices demonstrates our total commitment to delivering Sky News to anyone who wants to access it, wherever they are and however they want to access it."
Last week, Sky News unveiled a dedicated TV widget for the new Yahoo! Widget Engine which will give access to its latest news stories on selected IP-enabled TV sets.