Starting today, Steam users can download and play the open world action title for free until Sunday 9pm (GMT) / 1pm (PDT).
To coincide with the free trial period, the game can be unlocked permanently for £10.19 ($13.59), representing a saving of 66%.
Steam users can also save money on the game's DLC packs and digital strategy guide.
Saints Row: The Third was released for multiple platforms in November last year.
THQ has released numerous pieces of downloadable content, including the 'Genki Bowl VII' DLC, and last week's 'Gangstas in Space' pack.
Earlier this year, it was announced that the game's proposed Enter the Dominatrix expansion would be released as part of a full sequel.
> Read Digital Spy's review of Saints Row: The Third
> Saints Row: The Third stats revealed - two million Penetrator deaths
Watch a trailer for Saints Row: The Third below: