"We look forward to having him represent the United States in Japan," Nauert told reporters. "He spent good deal of time over there. I know he is steeped in the issues."
Earlier on Thursday, the US Senate approved Hagerty's nomination in a 86-12 vote.
Hagerty has been serving as the managing director of the private equity investment firm Hagerty Peterson & Company.
President Donald Trump nominated Hagerty for the post ambassador to Japan on March 27.