Jason Hale has announced on his Facebook page that he will not seek re-election for the Progressive Conservatives.
He says he plans to instead focus on his family and his cattle ranch.
Hale was elected in the riding of Strathmore-Brooks for the Wildrose party in 2012.
Late last year, he and 10 of his fellow Wildrose members, including then leader Danielle Smith, crossed the floor to join Premier Jim Prentice and the Tories.
The floor-crossers were harshly criticized for the move and two of them, Rob Anderson and Bruce Rowe, have already announced they are leaving politics.