Titled the 'Perpetual Testing Initiative', the DLC will be available for PC and Mac on May 8.
The free download features tools that will allow users to create their own puzzle rooms and import them to the Steam Workshop for other users to download.
The Steam Workshop launched in February along with mod creation tools for The Elder Scrolls V: Skyrim. Valve released its own Portal-themed Skyrim mod featuring the Space Core.
No plans for the 'Perpetual Testing Initiative' DLC were announced for the Xbox 360 or PlayStation 3.
Valve released Portal 2 for Xbox 360, PC and PlayStation 3 in April 2011.
> Read our review of Portal 2
Watch the trailer for Portal 2 below: