It is tipped to launch globally in late 2014.
A huge hit at the CES tech show currently ongoing in Vegas, the compact console fits snugly under a TV, offering Linux based PC gaming. Inside is a custom-built chassis to provide optimal thermal and acoustic management.
Alienware reps say its pet project will be competitively priced and "more powerful" than the Xbox One and PlayStation 4. Storage and Ram are yet to be announced.
Running Steam OS, Dell owned Alienware have been working on the Steam Machine project with Valve for some time.
13 other Steam Machine variants made by various collaborators were also revealed at CES by Valve but Alienware's version is likely to be the most available, globally.
"When Valve and Alienware began collaborating on our vision for a PC gaming console several years ago we could clearly see we were on to revolutionizing PC gaming forever," said Frank Azor, General Manager of Alienware.
"With the introduction of the X51 system nearly two years ago, Alienware kicked off an evolution of small form factor PC gaming systems designed for every living area."
In addition to the Steam Machine console, the Alienware X51 desktop will be available as a Steam Machine this year.
By offering the Steam Machine X51 ed., gamers will be able to choose between form factors.
Specific country availability and pricing will be announced closer to the launch date.