Hagerty will face Democratic candidate Marquita Bradshaw in the general election Nov. 3.
Hagerty announced his candidacy after Alexander, who has held office since 2002, announced that he would not run for reelection.
A native of Gallatin, Tennessee, Hagerty was appointed by President Donald Trump to serve as the U.S. Ambassador to Japan after working on the Trump transition team in 2016. His previous public service included serving under Gov. Bill Haslam as commissioner of the Tennessee Department of Economic and Community Development from 2011 to 2014.
Hagerty worked as managing director of Hagerty Peterson & Co., a merchant bank and private equity firm, before serving in Gov. Haslam’s administration. He had previously worked for Trident Capital, a private-equity investment firm headquartered in Silicon Valley, and as a management consultant with The Boston Consulting Group.
He also served in a domestic policy role in President George H.W. Bush’s administration.
Hagerty lives in Nashville with his wife, Chrissy, and their four children.