The Scotland international also has the option of a third year which could keep him at Molineux until 2016.
"Following on from a very successful loan spell in the Scottish Premier League with Hibernian, Leigh has come back and had an impressive pre-season," manager Kenny Jackett told the club's official website.
"I am very pleased that he has signed a new contract committing his future to the club. We hope that he can now continue his good goal-scoring form heading into the season."
Griffiths added: "I am delighted to have signed the new deal. The gaffer has been great with me from day one, he has seen what I can do and in return I have been rewarded with a new contract.
"That's me now, I'm settled. I'm moving into a new house in Wolverhampton tomorrow and from now on I can concentrate on my football and try to help Wolves have a successful season."