Jason was raised in Salem, Missouri, where he still owns the same family farm that was started by his great grandfather. He attended Salem High School, where he was an active member of FFA. At the University of Missouri-Columbia, Jason earned degrees in Agricultural Economics and Business Administration. After receiving degrees from both programs in three years, he attended law school at Oklahoma City University before returning home to serve his community. Back home in Missouri Jason began running the family farm and practicing law. It was during this time that he recognized the harm that the overbearing government was inflicting on Missourians and our economy. This inspired Jason to run for office himself so he could begin to undo the damage.

Jason was elected to the Missouri General Assembly in a special election in 2005.

In the General Assembly, Jason fought to shrink the size of state government, eliminate burdensome rules and regulations, increase government transparency, protect property rights, require drug testing for welfare recipients, and defend Missouri agriculture. Thanks to his efforts, Jason's colleagues selected him to serve in leadership- first as the Majority Whip and then as Speaker Pro Tem-one of the youngest in state history.

During a special election in June of 2013, Jason was elected to represent Missouri's Eighth Congressional District in the United States House of Representatives. He was re-elected in November 2014.

As a member of the 117th Congress, Jason serves as the Republican Leader of the House Budget Committee and the Ways and Means Committee. In Washington Jason has made a name for himself as a strong defender of rural Missouri and all of rural America. Jason is committed to fighting intrusive government regulations, increasing markets for farmers and ranchers, and protecting his constituents' rural way of life. Congressman Smith served in House leadership during all four years of President Trump's term from 2016 to 2020. Jason used this role as a platform to be a strong advocate for holding government and Washington accountable to the folks of Missouri.

In 2021, Jason was rated as the top conservative in the Missouri Delegation by the American Conservative Union; he is a life member of the National Rifle Association, pro-life and supports traditional values.

Jason attends Grace Community Church in Salem.