NatWest will sponsor the new domestic cricket competition to be played over 40 overs a side, the Pro40.
Ronnie Irani leads Totesport champs Essex in the NatWest Pro40
The England and Wales Cricket Board has signed a four-year deal with the bank which sees it retain sponsorship of all international limited-overs cricket.
ECB chief executive David Collier said: "We are delighted that NatWest has joined what promises to be an exciting and dynamic new county competition."
NatWest has ploughed more than £35m into cricket over the last 25 years.
It also remains a major supporter of grassroots cricket.
NatWest Pro40 takes over from the previous 45-over Totesport League.
A day-night match at Chelmsford on 18 July between Essex Eagles, the 2005 champions, and Northamptonshire Steelbacks will signal the start of the new-look competition.