Construction of the 'Nueva Mestalla' should be completed within two years and the agreement with Bankia included a medium-term loan of an unspecified amount, Valencia said on their website.
"This is an historic day that will delight... hundreds of thousands of Valencia fans, who will soon be able to see their team playing in one of Europe's best stadiums," club president Manuel Llorente said.
Valencia are one of many Spanish clubs to have suffered severe financial difficulties in recent years as they strived to remain competitive on the pitch while struggling to pay soaring wages and transfer fees.
The club had racked up debts of 471 million euros by the end of the 2009/10 season, according to a study published in February by an accounting professor at the University of Barcelona.
Only Real Madrid and Barcelona, the world's richest clubs by income who earn far more than their La Liga rivals from merchandising and television rights, were deeper in the red, the study showed.
Valencia, who have been forced to sell prize assets including Spain internationals David Villa and David Silva to stay afloat, are currently third in La Liga, which would give them a lucrative berth in next season's Champions League.
They were eliminated from this season's edition of Europe's elite club competition last week by English club Chelsea.
