LaHood is the son of Ray LaHood, the former United States Secretary of Transportation and before then the seven term congressman from the district his son currently represents. He has called himself a fiscal conservative focused on budget issues.
While his father was a moderate Republican, LaHood is considered more conservative.
LaHood was born in Peoria, Illinois to Ray and Kathy LaHood, as the eldest of four siblings, and went to Academy of Our Lady/Spalding Institute there. He graduated from Loras College in Iowa, and later went on to receive his J.D. from John Marshall Law School.
LaHood was a prosecutor in the Tazewell County state's attorney's office and the United States Attorney's Office for the District of Nevada in Las Vegas. On returning to Peoria in 2005, he took up private law practice; as of 2011 he is in the Peoria law firm of Miller, Hall & Triggs.
LaHood ran for Peoria County state's attorney in 2008, losing to incumbent Kevin Lyons by a margin of 43,208 to 36,449. He was also involved in several other Republican campaigns, including Bill Brady's 2010 campaign for governor and Dan Rutherford's campaign for Illinois Treasurer.
LaHood was appointed to the Illinois Senate on February 27, 2011, at the age of 42. He took office March 1, the day after Dale Risinger retired. When appointed, LaHood announced he would run for election to a full term in 2012, which he won, running unopposed.
On July 7, 2015, LaHood defeated Mike Flynn 69%-28% in the GOP Primary to become the Republican candidate for Illinois's 18th congressional district, replacing Aaron Schock. He faced the Democratic candidate Rob Mellon in the September 10 special general election, easily defeating him with a large percentage of the vote. He was sworn in by House Speaker John Boehner on September 17, 2015.
In the November 8, 2016 general election, LaHood defeated Democratic candidate Junius Rodriguez by a margin of 250,506 (72.1%) to 96,770 (27.9%).
LaHood was appointed to two House committees after his special election win in September 2015. He currently serves on the House Committee on Natural Resources and the Committee on Science, Space, and Technology.
On May 25, 2016, LaHood introduced legislation through the Science, Space, and Technology Committee that approved the Networking and Information Technology Research and Development (NITRD) Modernization Act of 2016. The NITRD Program was originally authorized by the High Performance Computing Act of 1991. NITRD is the federal government's primary research portfolio on transformative high-end computing, high-speed networking, high capacity systems software, cybersecurity, and related advanced information technologies.
Darin LaHood drew criticism from constituents for declining to hold an open town hall during the February 2017 recess. Constituents from across the 18th congressional district gathered in Bloomington Normal and Jacksonville to request a town hall to discuss a variety of issues, including access to health care, immigration laws, and the freedom of the press. LaHood spoke to the demonstrators outside the Farm Bureau building in Peoria who had come to push for a town hall, LaHood stated, "We live in a democracy, people may not always agree with me and that's why I have to go before voters like I did in November. I was fortunate to receive 72 percent of the vote in that election. But this is part of the process."
LaHood lives in Dunlap with his wife Kristen; they married in 1992. They have three children: McKay, Lucas, and Teddy.