Nobody knows when Middelfart was founded, but it plainly owes its existence to the crossing. The town had its first privileges by the end of the thirteenth century, at a time when fishing mattered as much as the ferry running over to Snoghøj on the Jutland shore; King Hans granted it the same rights held by Odense and Assens in 1496, and later kings confirmed them in 1540, 1569 and 1596. In the sixteenth century cattle export became significant — Jutland herds crossed here on their way east.

The harbour came late. Gammel Havn, the old harbour, dates only from the 1830s, and was extended and dredged eastward at the start of the twentieth century. Before that, Middelfart worked directly off the beach, which is exactly how its strangest industry operated.

From the Middle Ages onward, Middelfart specialised in something no other Danish town did in quite the same way: it hunted harbour porpoises. The animals migrate through the Little Belt each winter, funnelled by the same narrowing that gave the town its name, and the hunters used the geography against them. By beating the water with sticks and branches, crews drove the porpoises out of the channel and into shallows where they could be taken.

Guild regulations survive from 1593, and the practice was already old by then. The value was in the blubber, rendered down into oil that lit lamps indoors and out. In the second half of the nineteenth century a season could yield seven or eight hundred animals; in the exceptional winter of 1854–55 the hunters landed 1,742, though a normal winter brought half that or fewer. What ended the hunt was not sentiment or law but the electric light, which made lamp oil close to worthless. The guild wound itself up late in the nineteenth century, and the hunt returned only briefly during each of the two world wars, when scarcity made it worth the trouble again. Two memorial stones now mark where the animals were brought ashore and where the blubber was boiled.

Middelfart Church, dedicated to St Nicholas, stands near the harbour at the end of Algade, assembled in stages over three centuries: a Late Romanesque chancel, a tower first raised in the fourteenth century, a nave with aisles from the late fifteenth, and a richly carved altarpiece from 1650. On Brogade, Henner Friisers Hus — half-timbered, built around 1575 — is now part of Middelfart Museum, its restoration completed in March 2014.

The town's twentieth century arrived in steel. The first Little Belt Bridge opened in 1935, and Middelfart stopped being a ferry town and became a junction; a motorway bridge followed in 1970. The population figures track the change without needing commentary: 2,345 in 1880, 11,056 by 1950, and 16,958 at the start of 2026.

Modern Middelfart put its civic heart on the water. Kulturøen — literally 'Culture Island' — gathers the public library, a cinema, a restaurant, a café and the tourist office into a single waterfront building looking out at the strait and the bridges.

For a town of this size it has an improbable athletic record. Middelfart hosted the 1998 UCI World Cyclo-cross Championships, and fields its football side, Middelfart G&BK. Christian Eriksen was born here in 1992, as was Rasmus Falk; the rowers Rasmus Quist Hansen and Søren Madsen both came home with Olympic medals; and the speedway rider Jan O. Pedersen, born in 1962, took the world title in 1991. The town's list of natives runs deeper than sport — Frida Schmidt (1849–1934), teacher, suffragist and a pioneer of the Danish Women's Society, and the theologian and politician Frederik Julius Bech (1758–1822) among them.