It will be shipped in July.
Nvidia's graphics chips are well-known to enthusiasts in their 20s who deck out desktop computers with high-end components to get the best out of first-person shooters and other games.
The Santa Clara, California company hopes some of those customers will also be drawn to Shield, which uses Nvidia's Tegra 4 mobile chip, has a pop-up retina display, and runs the same games as those on Android tablets and smartphones.
The portable device also shows movies, plays music, stores e-books, and can be used to surf the Web.
As PC sales suffer from the growing popularity of tablets, Nvidia has staked its future on using its PC graphics expertise to make high-performance processors for mobile devices.
Last week Nvidia cut the price of the Shield to $299 from $349.