Since founding the company with Antonio Carluccio in 1999, Kossoff has built the brand up to over 100 stores in the UK and internationally.
He will leave his role with immediate effect from 31 July.
Kossoff said: “It's been a fantastic journey and I am desperately proud of the team and what they have achieved. However, after 17 years it really is time to let our CEO Neil Wickers take it forward and for me to focus on other things.”
Owner Renuka Jagtiani described Kossoff as ‘integral’ to guiding Carluccio’s growth from a start-up to one of the country’s leading high street restaurant brands.
“We want to wish him the very best for the future, he will be missed by the whole team,” said Jagtiani.
Carluccio’s reported a 7.4 per cent rise in turnover to £137.8m for the year ending September 2015, after opening 14 new restaurants in the UK, Ireland and USA.
The group launched the first of its ‘new generation’ of restaurants in London this year, complete with pizza menu, grab-and-go food station and retail area.