The sleek image is set against a mountain backdrop and depicts a red Dodge Viper.
The game's box art, meanwhile, also features a mountain range, as well as what appears to be a festival taking place in the background.
The image suggests that the racer will contain an open-world element, while the flashing lights coincide with the concert footage that appeared in the game's debut trailer.
Announced in March, little is known of the spinoff racer, with Microsoft promising to reveal more at this year's E3 event in Los Angeles.
It will be developed by Playground Games, a UK studio created by former DIRT, TOCA and Colin McRae developers, which Forza studio Turn 10 described as a "partner".
Forza Horizon will be released exclusively on Xbox 360 later this year.
It follows last year's critically acclaimed racing title Forza Motorsport 4.
Watch the Forza Horizon teaser trailer below: