McPhee held the Washington Capitals' general manager post for 17 seasons before his firing in 2014. He owns more than 22 seasons of management experience in the NHL, receiving his start with the Vancouver Canucks in 1992.
"George brings a tremendous amount of experience and insight to our front office," Snow said in an official team statement. "His ability to evaluate players along with his managerial skills, are an asset that we're thrilled to add to our Hockey Operations Department."
Washington had eight 40-win seasons under McPhee and captured the Presidents' Trophy in 2009-10.