Everton claims the deal is the biggest shirt sponsorship deal in its history and means that Chang will be shirt sponsor of the Blues up until 2014.
A number of senior personnel from the football club, including midfield star Marouane Fellaini, flew to Thailand, to finalise the contract.
Everton has been wearing Chang's distinctive elephant logo on its shirts since the start of the 2004/2005 season.
Robert Elstone, Everton chief executive, said: "It is a great deal for us financially. It is probably about four times the original deal and is at least 25% more than the current deal, so we are showing good growth rates."
As part of its on-going commercial relationship with Chang, Everton has helped develop young Thai footballers and improve the country's coaching infrastructure.
Chang is owned by Thai Beverage company, one of the biggest drinks companies in South East Asia.
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