The team made the announcement on its website Monday.
Keenan, 63, coached seven different teams over 20 years in the National Hockey League. He won a Stanley Cup with the New York Rangers in 1994. He most recently coached the Calgary Flames for two seasons from 2007 to 2009.
He recorded his 600th career win with the Flames, but was fired with a year left on his contract after the Flames lost in the first round of playoffs for a second year.
Keenan will replace former Carolina Hurricanes coach Paul Maurice, who coached Metallurg this past season and reportedly turned down a contract extension.