Four of the Leith senior staff have founded the as-yet unnamed agency to handle the account for Scotland's top-selling lager. The account was resigned by The Leith Agency in August.
Jonathan Shinton, a board director and the head of account management, Gareth Howells, the agency's deputy creative director and head of art, the senior writer Zane Radcliffe and the associate planning director, Ken Dixon, head the new agency which opens on 1 January 2003.
The Leith Agency is due to handle the Tennent's business until December.
The appointment of the new agency ends speculation that the account would move south of the border, and comes as Tennent's prepares for rival Coors Brewers' launch of its Carling brand in Scotland.
Leith ended its 13-year partnership with Tennent's in August when it picked up the £8 million Coors Brewers accounts for Worthington's, Caffrey's and Reef from Roose. It was awarded the business on the back of its work for the Carling and Grolsch brands.
Radcliffe said: "In the past few years, Scotland has changed. Unfortunately many of the top agencies haven't been alive to change, not in their work or the way they operate. Tennent's has given us a wonderful springboard to do something fresh, both creatively and culturally."
Sandra Mitchell, the head of marketing for Tennent's, added: "We get continuity for our creative plans and increased flexibility and energy from an award-winning team. And we get to keep the business in Scotland."