The win followed a review that pitted JWT against Lowe London. Media will remain with MindShare.
The brief is to produce a TV, press and online campaign for Heaven. The work is expected to break in early 2008.
The appointment will come as a blow for Lowe, which was hoping to regain the place on the Nestle roster it lost to JWT in February 2005.
JWT now handles all Nestle's UK confectionery advertising, following a realignment of ad arrangements by the Swiss-based company that saw Lowe lose brands including Quality Street, Milkybar and Aero.
Nestle launched the Heaven brand in the UK in January this year. Made from Swiss chocolate, Heaven is available in block and gift-pack varieties in five flavours.
The launch, which was backed by an advertising campaign created by JWT Australia, came just a year after Nestle scrapped its luxury Double Cream line due to poor sales.