The 2018 United States House of Representatives elections in Arizona were held on November 6, 2018, to elect the nine U.S. representatives from the State of Arizona, one from each of the state's nine congressional districts. The elections coincided with the 2018 Arizona gubernatorial election, as well as other elections to the U.S. House of Representatives, elections to the United States Senate and various state and local elections. The 2018 general elections saw the Democratic party gain the 2nd congressional district, thus flipping the state from a 5–4 Republican advantage to a 5–4 Democratic advantage, the first time since the 2012 election in which Democrats held more House seats in Arizona than the Republicans.
