The spot opens on two women sitting in a sunny park. One has a Maltesers ice-cream, and the other is angling for a bite.
She manages to get a mouthful, to the disgust of her friend, who calls her a "cheeky mare".
The TV ad will run from 1 May until July in key peak-time slots to maximise the brand's exposure in the run-up to the ice-cream sector's key summer selling period. Posters will also be rolled out from 1 July for six weeks.
Media was planned through MediaVest and bought by Zenith.
The campaign will run alongside a current advertising push for the core Maltesers brand, which features both TV and poster work.
A Mars spokeswoman, Sue D'Arcy, said: "Although the sun doesn't have to shine for consumers to enjoy the Maltesers ice-cream, the next few months are a key time for ice-cream sales, and we will be looking to maximise these with the launch of this advertising campaign."
Brand extension in the countline sector has become a key revenue stream for confectionery manufacturers.
Mars recently axed four lines to concentrate on high-profile brands such as Mars, Snickers, Twix and Maltesers.
The ads were written by Angus MacAdam and were art directed by Paul Jordan.
The TV spot was directed by David Hartley through Brave Films.