With Republican Representative Randy Neugebauer of retiring in 2016, Arrington decided to run for his seat. Glen Robertson led a nine-candidate field in the primary election held on March 1 with 27,791 (26.7 percent) of the ballots cast, followed by Arrington's 26,980 (26 percent). In third place was Michael Bob Starr, the former commander of Dyess Air Force Base who led handily in Abilene and finished with 22,256 votes (21.4 percent). Laredo surgeon Donald R. May finished fourth with 9,592 votes (9.2 percent). In the runoff election held on May 24, 2016, Arrington defeated Robertson, 25,214 (53.7 percent) to 21,769 (46.3 percent) to become the Republican nominee. He faced no Democratic opponent in the congressional general election on November 8, 2016. Arrington polled 176,314 votes (86.7 percent); the Libertarian Troy Bonar trailed with 17,376 votes (8.5 percent), and the Green candidate, Mark Lawson, polled 9,785 votes (4.8 percent). However, the 19th is so heavily Republican that any Democratic challenger would have faced nearly impossible odds in any event. With a Cook Partisan Voting Index of R+26, the 19th is the third-most Republican district in Texas and the 12th-most Republican district in the nation. When Arrington took office on January 3, 2017, he became only the fifth person to represent this district since its creation in 1935. Arrington supported President Donald Trump's 2017 executive order curtailing Middle Eastern immigration. He stated that "It is important that our commander in chief puts the safety of Americans first. Given concerns about the inadequate vetting of refugees and problems with our immigration system, this temporary pause is intended to ensure the safety of our citizens." In defending a proposal to cut access to the SNAP program (food stamps), Arrington cited the biblical passage Thessalonians 3-10. "He says even when we were with you we give you this rule, 'If a man will not work he shall not eat.' And he goes on to say 'We heard that some of you are idle.' I think that every American, Republican or Democrat wants to help the needy among us. And I think it's a reasonable expectation that we have work requirements. I think that gives more credibility, frankly, to SNAP." In July 2019, Arrington voted against continued support for the 9/11 fund for first responders.