The news comes as Zizzi is extending its group of 109 restaurants while refurbishing existing restaurants.
As part of the campaign, Mischief will also work on a 'fresh talent’ initiative, which seeks to provide professional opportunities within Zizzi restaurants for graduates who specialise in art, illustration, design, ceramics and other creative disciplines.
Mischief, led by MD Mitchell Kaye, will also run a press office function around food specials.
The budget is not disclosed. It is an initial 6-month contract.
Mischief consultant Jude Forbes will head up the account, reporting to Zizzi marketing director Liz Norris.