The 2012 Arizona House of Representatives election took place on Tuesday, November 6, 2012, with the primary election held on Tuesday, August 28, 2012. Arizona voters elected all 60 members of the Arizona House of Representatives in multi-member districts to serve two-year terms.
The election coincided with United States national elections and Arizona state elections, including U.S. President, U.S. Senate, U.S. House, and Arizona Senate.
Following the previous election in 2010, Republicans held a 40-to-20-seat majority over Democrats. During the legislative session, Representative Daniel Patterson switched political party affiliation from Democrat to Independent on April 2, 2012. On April 11, 2012, Patterson then resigned from the House. On April 23, 2012, Nicholas "Nick" Fontana (I) was appointed by the Pima County Board of Supervisors to fill the House vacancy in Legislative District 29. Additionally, Democratic representative P. Ben Arredondo resigned from the House on October 5, 2012. Given both the proximity to the end of the term in December and that the legislature was in recess for the remainder of the session, the Maricopa County Board of Supervisors decided not to replace Arredondo and simply left the seat vacant. Therefore, on election day in 2012, Republicans had 40 members, Democrats held 18 seats, there was one Independent, and one seat was vacant.
Republicans maintained their majority in 2012, though the GOP majority narrowed to 36 seats. At 24 members, Democrats experienced a net gain of six seats. The newly elected members served in the 51st Arizona State Legislature, during which Republican Andy Tobin was re-elected as Speaker of the Arizona House.
These were the first elections in Arizona following the 2010 United States redistricting cycle, which resulted in redrawn legislative district boundaries.
Italics denote an open seat held by the incumbent party; bold text denotes a gain for a party.
Sources for election results:
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Green Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Green Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Green Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Libertarian Party Primary Results |-
|- !colspan="5"|Green Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Green Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Libertarian Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-
|- !colspan="5"|Republican Party Primary Results |-
|- !colspan="5"|Libertarian Party Primary Results |-
|- !colspan="5"|Democratic Party Primary Results |-