Since the 1960s, Tarrant County has been fairly conservative for an urban county, and one of the most populous Republican-leaning counties in the nation. However, it elected Democrat Jim Wright to 17 terms (1955-1989) as U.S. Congressman and Speaker of the House (1987-1989), and Wright was succeeded by fellow Democrat Pete Geren (1989-1997).

In 2018, the Democratic Party rebounded to represent a larger portion of the political profile and made huge gains in Tarrant County, concentrated in several areas throughout the county: eastern Euless, Grand Prairie and eastern and southern Arlington, northern and western areas of Mansfield, large portions of Fort Worth, particularly the area surrounding the Stockyards and Meacham Airport, southern and eastern Fort Worth, especially in dense metro areas and along I-35W, and Forest Hill.

Republicans are dominant in many of the rural areas of the county, downtown and western Fort Worth and north of Loop 820, and almost all suburban areas including Benbrook, rural Mansfield areas and western Arlington, Haltom City, Mid-Cities (Hurst, Euless, and Bedford), and the northern suburbs.

Beginning in 1952, the majority of voters supported the Republican Party presidential candidate in every election except 1964, when Tarrant County voted for the Lyndon B. Johnson-Hubert Humphrey Democratic ticket, then again in 2020 when the Joe Biden-Kamala Harris Democratic ticket carried the county. In 2016, Donald Trump-Mike Pence won Tarrant with 51.7% of the vote, the worst showing for Republicans since the Bob Dole-Jack Kemp ticket in 1996 won by a margin of 8.6%, and closest since 1976 when Gerald Ford-Bob Dole carried the county by less than 1% over the Jimmy Carter-Walter Mondale ticket.

The first Republican elected to the State Senate from Tarrant County since Reconstruction was Betty Andujar in 1972.

The county has leaned Republican in United States Senate races since Democrat Lloyd Bentsen's 1988 victory, but in the 2018 election Democratic candidate Beto O'Rourke carried Tarrant, though losing statewide to incumbent Ted Cruz.

In 2020, Joe Biden carried the county with 49.3% (to Donald Trump's 49.1%) in the 2020 presidential election, the first win for a Democratic presidential ticket in Tarrant County since Texas native Lyndon B. Johnson in 1964 and the closest race in the county since 1976, which was won by the razor thin margin of 1,826 votes (The margin of votes in 2020, in comparison, was 1,836 votes). Many other suburban Texas counties, including Tarrant's immediate neighbors in Denton County and Collin County as well as those around Houston and Austin, have shown similar trends since 2016.

From the 1893 beginning of U.S. House District 12, there have been two Republicans in 127 years elected to the U.S. House for the western half of Tarrant County; from the 1875 inception of U.S. House District 6, there have been three Republicans in 145 years elected to the U.S. House for the eastern portion of Tarrant County, including former congressman and senator Phil Gramm's election as both a Democrat and a Republican after he switched parties in 1983 to run for re-election.