Nick has been editor of the Northcliffe-owned title for more than 15 years.
He is leaving to become the first chairman of the Leicester and Leicestershire Economic Development Company.
The new body has been set up by the city of Leicester and county councils to help drive economic growth across the area. It will seek to work with organisations across the county to create new jobs, improve skills and promote business growth.
“As many of you will know, Nick has had a long, distinguished career with Northcliffe. He joined in 1987 and has edited the Mercury since 1993. I have no doubt that in his new role he will continue to have strong and cordial links with the Mercury.
“I trust you will all join with me in wishing Nick every success in this exciting, new opportunity.
“An announcement on Nick’s successor will follow in due course.”