The launch came the day before Computex, Asia's biggest technology trade show opens its doors in the capital Taipei.
Asus chief Jonney Shih showed off the Transformer Book V in front of a packed house of hundreds of industry leaders, experts and media from around the world.
"In each of the modes, we offer an uncompromised experience, no matter whether for communication, productivity or entertainment," Shih said.
In a further attempt by the company to diversify into the mobile market, the device has five modes, as a laptop and detachable tablet running both Android and Windows operating systems and as an Android phone.
The five-inch phone docks into the tablet and promises speeds up to four times faster than 3G. As a laptop, one "hardware button" switches between the two operating systems.
Asus made its name making motherboards but is now the world's number three tablet seller, with a five percent share, and fifth in the PC rankings.
The Transformer Book V was met with applause from the audience.
"I like that it's a five-in-one -- it's a case of convenience, having everything in one device," said Antonin Lee of Taipei-based YouTube channel Techalook.
But it also has its limitations, Lee said.
"It's not for someone who wants a high-end smartphone or hardcore gamers who would need something more powerful, it's more for the mid-range user. It's about convenience rather than performance," Lee added.
Computex is set to attract 130,000 visitors over four days and will see the launch of 40 new products this year, with Microsoft, Intel and Ford among the leading global brands attending.