Sean Patrick Duffy was born on October 3, 1971, in Hayward, Wisconsin. The tenth of eleven children born to Carol Ann and Thomas Walter Duffy, he was raised in a large Irish Catholic family. From the age of five, he developed a passion for lumberjack sports and went on to become a champion speed climber.

After graduating from high school, Duffy earned a bachelor’s degree in marketing from Saint Mary’s University of Minnesota and later received his law degree from William Mitchell College of Law in St. Paul, Minnesota. Duffy’s media career began when he appeared on the MTV reality-show, The Real World: Boston, in 1997. His political career began in 2002 when he was appointed district attorney of Ashland County, Wisconsin, as a Republican. He resigned as district attorney in 2010 to focus on his campaign for the U.S. House of Representatives.

His national political rise began that same year when he was elected to Congress during a wave of Republican victories, presenting himself as a grassroots political outsider. Representing Wisconsin’s 7th district, Duffy served nearly nine years in the House of Representatives, gaining influence on the House Financial Services Committee.

In 2019, Duffy stepped down from Congress, citing family responsibilities, and he returned to media. He briefly served as a political commentator for CNN. He later joined BGR Group as senior counsel and an advisory board member, representing major clients in the financial services and aviation industries. In January 2023, he became co-host of The Bottom Line on Fox Business.

On November 18, 2024, President-elect Trump nominated Duffy to serve as secretary of Transportation. The full Senate confirmed Duffy on January 28 in a 77–22 vote, and he was sworn in the same day.