The announcement by Bank of Ireland was made at a reception in NUI Galway on Monday evening when the Connacht squad for the 2007/08 season was unveiled.
"It is a great boost for Connacht Rugby and we are delighted that Bank of Ireland will be on board again. We have built up a strong relationship over the years and we are very much looking forward to continuing that," said Connacht Rugby CEO Gerry Kelly.
Donal Flynn, Bank of Ireland's Regional Manager for the west, said he was pleased that Bank of Ireland would again be the main sponsors of Connacht Rugby.
"We have enjoyed a very good relationship with Connacht Rugby over the years and have been proud to be part of their success story," he said.
Connacht will play their first pre-season game when they host South Africa at the Sportsground in a sell-out match next Tuesday.
Connacht will also play pre-season games against French Top 14 side Castres at the Sportsground on August 28 and September 1 before travelling to London the following week to play NEC Harlequins at the Stoop.
The westerners open their Magners League campaign against Newport Gwent Dragons in Galway on Friday, September 21.