Before European settlement, the land that comprises Flemington, as was all of Hunterdon County, was the territory of the Lenni Lenape Native Americans.

In 1712, as part of a land parcel of 9,170 acres (37.1 km2), the Flemington area was acquired by William Penn and Daniel Coxe.

Early German and English settlers engaged in industries dependent on farm products.

As time passed poultry and dairy farms superseded crops in agricultural importance.

An example of early settlement families was Johann David and Anna Maria Ephland, who emigrated in 1709 from Germany through London to New York and settled on his 147.5-acre (0.597 km2) farm in 1717.

On December 14, 1776, during the American Revolutionary War, a party of British dragoons led by Cornet Francis Geary raided a store owned by Thomas Lowrey near the Presbyterian Church in Flemington to seize a supply of guns.

On their return to Pennington, local militia led by Captain John Schenck ambushed them and killed their commander.

Fire destroyed the old courthouse in 1826 and the City of Lambertville made an ultimately unsuccessful attempt to have the seat relocated there.

Flemington remained the County Seat and the Courthouse which stands today on Main Street was built.

[citation needed] Present-day Flemington was originally formed as a town by an act of the New Jersey Legislature on March 14, 1870, within portions of Raritan Township.

The purpose of this Fair was to promote competition between farmers, stock raisers and machinery manufacturers.

On February 13, 1935, a jury in Flemington found Bruno Richard Hauptmann guilty of the kidnapping and murder of Charles Lindbergh's baby boy.

[25] The Union Hotel, opposite the courthouse in which this trial took place, housed several journalists reporting on the event.

[6] The borough form of government used by Flemington, the most common system used in the state, is a "weak mayor / strong council" government in which council members act as the legislative body with the mayor presiding at meetings and voting only in the event of a tie.

The mayor can veto ordinances subject to an override by a two-thirds majority vote of the council.

[47][48] As of 2023[update], the mayor of Flemington Borough is Republican Marcia A. Karrow, whose term of office ends December 31, 2026.

Engelhardt (D, 2025), Malik Johnston (D, 2023), Anthony "Tony" Parker (D, 2024; elected to serve an unexpired term) and Elizabeth Rosetti (D, 2024).

[3][49][50][51][52][53][54] In January 2019, the borough council selected Jeffrey Doshna from a list of three candidates selected by the Democratic municipal committee to fill the seat expiring in December 2020 that was vacated by Betsy Driver when she took office earlier that month as mayor.

[60][61][62] For the 119th United States Congress, New Jersey's 7th congressional district is represented by Thomas Kean Jr. (R, Westfield).

[64] For the 2024-2025 session, the 16th legislative district of the New Jersey Legislature is represented in the New Jersey Senate by Andrew Zwicker (D, South Brunswick) and in the General Assembly by Mitchelle Drulis (D, East Amwell Township) and Roy Freiman (D, Hillsborough Township).

It is one of only a rapidly diminishing number of New Jersey's once-widespread traffic circles still extant according to its original design.

The circle also sees a higher rate of traffic accidents and violations than any other region of Flemington and Raritan Township.

Unlike most circles, traffic on US 202 does not yield on entry; US 202, being a main four-lane divided highway, gets the right of way.

The intersection of Route 12 and Main Street west of the Flemington Circle was converted to a roundabout in 2009.

[117] Trans-Bridge Lines provides frequent daily bus service, west to Doylestown / Bethlehem, Pennsylvania, and east to Newark Liberty International Airport, the Port Authority Bus Terminal in Midtown Manhattan and John F. Kennedy International Airport.