Everett McDonald, the backbencher for Grande Prairie Smoky, becomes the new associate minister for agriculture.
Olson is expected to be away for a few weeks after undergoing an islet cell transplant.
He told followers on Facebook that he is doing well and resting comfortably.
Prentice also announced that Municipal Affairs Minister Diana McQueen will take on additional responsibility for Alberta’s action on climate change.
He says McQueen will work with Environment Minister Kyle Fawcett and others in cabinet on the strategy to fight greenhouse gas emissions.