Surrey have agreed what they say is "the biggest sponsorship deal in English club cricket history". No figures have been revealed but the five-year deal with Brit Insurance will run until the end of the 2010 season.
"These are exciting times for Surrey County Cricket Club," said the club's chief executive, Paul Sheldon.
"With the completion of the redevelopment of the Vauxhall End we can proudly boast one of the finest arenas in world cricket."
He added: "The support of Brit Insurance will be absolutely crucial in helping us to achieve our objectives both on and off the pitch."
The company's logo will appear on all first team kit for both Championship and one-day matches and they also retain the name rights for The Brit Oval.
The new contract also includes performance based incentives which will reward the team if they achieve promotion back to Division One of the Championship.