Facebook founder Mark Zuckerberg said: "I grew up with the internet, but only a third of the world is on it today. We are really close to the beginning of this. The majority of people in the world have never seen anything like what you and I would call a computer."
Facebook's bold new look for Android becomes available from April 12.
Facebook is unveiling what's expected to be a big change in the way millions of mobile users access the site on their mobiles. The company gave little away before today's event in the US about its "new home on Android", but it could mean a new homescreen for many smartphones.
The launch of an "enhanced app" will reinforce Facebook's "mobile first" as users increasingly monitor the social networking site from smartphones and tablets, rather than desktop computers.
According to Facebook, more than 680 million of its one billion users now check the social network from mobile devices.
Ernest Doku, telecoms expert at comparison site uSwitch.com, said the arrival of a 'Facebook phone' would mark a new departure for mobile devices.
"After a protracted journey to market, the 'Facebook phone' finally seems set to arrive," he said.
"The device is a concerted bid for Facebook to make a play for the eyeballs of millions of consumers, and become the hub from which they interact with all aspects of their smartphone.
"The important word on Facebook's invitation is 'home'. We should expect Facebook to greet mobile users when they turn their smartphones on in the morning, and to be the core of the user's experience - integral to searching, surfing and interacting."
He added: "This forthcoming device will be the tip of the spear - a focused showcase of what is possible with deeper Facebook integration - and is certain to mark the start of future devices which embed the social network into the fabric of functionality, from a number of manufacturers."
Both Facebook and HTC have refused to comment on the speculation surrounding the announcement.