Smith, 59, the older brother of Warrington and former England coach Tony Smith, has taken over from Matt Elliott, who has stepped down from the role due to his commitments with New Zealand Warriors.
The pair worked together at Bradford at the start of Super League in 1996.
Smith, who also had a spell in charge of Hull and was a consultant with England during the 2010 Four Nations Series in Australia and New Zealand, said he had long-held ambitions to help develop rugby league in the States.
"The potential for the game in America is enormous," he told Brisbane's Courier-Mail. "American people go nuts over our game.
"Matt Elliott has been fantastic for the Tomahawks and I just want to dovetail on the back of that.
"I have had long-running connections to the game in America, beginning with a great friendship with Mike Mayer, who was one of the men who introduced the game to the States in the 1970s.
"I have been to America many times and I always take videos with me and, when you actually sit down and explain the strategy, they truly embrace and understand it."
The Tomahawks, who beat Jamaica to qualify for their first World Cup, face the Cook Islands, Scotland and Wales in their group matches.