When the Democratic Representative Robert L. "Robby" Cook, III, of Eagle Lake in Colorado County, then located in District 17, declined to seek a seventh term in 2008, Kleinschmit, unopposed for his Republican nomination, won the open seat by defeating another Democrat, Fayette County rancher Donnie Dippel, 32,208 votes to 25,561. Representative Kleinschmidt is a member of the House committees on Agriculture and Livestock and Homeland Defense and Public Safety. He is the chairman of the House Republican Caucus Policy Committee. In the 2013 legislative session, Kleinschmidt supported a ban on abortion after twenty weeks of gestation; the bill passed the House, 96-49. He voted for companion legislation to increase medical and licensing requirements of abortion providers. Texas Right to Life rated him 64 percent in 2013 and 60 percent in 2011. Kleinschmidt voted against a taxpayer-funded breakfast program for public schools; the measure passed the House, 73-58. He co-sponsored legislation to provide marshals for school security. He opposed the bill requiring the immunization of minors without parental consent, a measure which the House nevertheless approved, 71-61. He co-sponsored the law to extend the franchise tax exemption to certain businesses. Kleinschmidt voted against the measure to prohibit texting while driving, but he had voted for such a ban in 2011. He voted to require testing for narcotics of those receiving unemployment compensation. He voted against an "equal pay for women" measure, which passed the House, 78-61. He voted to forbid the state from enforcing federal regulations of firearms and co-sponsored another law allowing college and university officials to carry concealed weapons in the name of campus security. He voted for the redistricting bills for the state House, the Texas Senate, and the United States House of Representatives. He opposed term limits for certain state officials. In 2011, Kleinschmidt voted to cut spending on state agencies. That same year, he opposed a ban on smoking in public places. In 2013, Phyllis Schlafly's Eagle Forum, managed in Texas by Cathie Adams, a former state chairman of the Texas Republican Party, rated Kleinschmidt 85 percent favorable. The Young Conservatives of Texas rated him a cumulative career score of 74 percent. He ranked 66 percent from the Texas League of Conservation Voters and 33 percent from the Sierra Club. The interest group, Texans for Fiscal Responsibility, founded by Michael Quinn Sullivan, rated him 66 percent in 2013 and 50 percent in 2011. Both the Texas Association of Business and the National Rifle Association rated him 100 percent. In April 2013, Kleinschmidt suspended his legislative chief of staff, John Higgins, Jr., after Higgins was indicted on twelve felony charges stemming from allegedly falsifying travel reimbursements. Rosemary Lehmberg, the district attorney of Travis County in Austin, said that Higgins was released from custody after he posted a $10,000 bond. He was charged by a Travis County grand jury. Kleinschmidt defeated Democrat Carolyn Banks for re-election in 2014. He resigned in January 2015 to serve as general counsel in the Department of Agriculture. He was replaced in the House by fellow Republican John Cyrier in a special election.
