Kean is now in charge of things until 2013 after initially taking over on a temporary basis after Sam Allardyce was sacked in December.
However, club owner Anuradha Desai signalled her intention to give Kean a long-term deal earlier this month, and has now delivered.
"I am delighted to commit my future to Rovers at the start of what I see as a massively exciting new era for the club," Kean told the club's website.
"The owners have shown great faith in me and I will do all I can to repay them.
"This is a great opportunity for me and I intend to grasp it with both hands."