The brief will be the first work the independently owned agency, part of the Karma Communications Group, has produced for the snacks and soft drinks giant.
The integrated campaign will launch in the UK later in the spring and is likely to include national press, digital and radio work.
Karmarama picked up the brief for the campaign after a competitive pitch against undisclosed agencies.
The coated peanuts have tiger-patterned shells and come in flavours based on Walkers' crisp varieties, such as salt and vinegar and smoky bacon.
PepsiCo plans to tap into an emergent mass-market snack sector, as the flavoured nuts category grew by 36% between 2010 and 2012, according to Nielsen figures.
Abbott Mead Vickers BBDO is the main creative agency for PepsiCo's brands in the UK, including Walkers, and is not affected by the win.
OMD UK will handle media planning and buying for the new brand, after PepsiCo consolidated its UK media into the agency last year.