The Triangle Region (Danish: Trekantområdet [ˈtʁeːkandˌ⁠ɔ⁠mʁoðəd]) is a cooperation consisting of seven Danish municipalities on the Danish peninsula of Jutland and the island of Funen: Billund, Fredericia, Haderslev, Kolding, Middelfart, Vejen and Vejle. It is not an official administrative Region of Denmark.

The Triangle Region began as the general term for the industrial and communications hubs of Kolding, Vejle and Fredericia in the early 1960s. The three cities (thus ‘triangle’) originally worked together to coordinate and collaborate locally, but have since expanded into a cooperation between seven municipalities, which together have 421,480 inhabitants (as of 1 January 2018) and cover an area of 4,266.0 km².

An area of political and economic stability, the Triangle Region is often regarded as Denmark’s third major region after Aarhus and Copenhagen. It has a reputation for having lower levels of pollution, crime and traffic problems than the big cities.

The Triangle Region was historically an industrial area with an emphasis on production and logistics but more recently, it has become a hub for entrepreneurs, tourism and energy companies. A formal cooperation between municipalities in the region began in 1994 and the current Triangle Area Denmark was established in 2007 by the new municipalities of Billund, Fredericia, Kolding, Middelfart, Vejen and Vejle. Haderslev joined in 2016.

Billund was first mentioned as "Byllundt" in the year 1454 and as "Billund" in 1510. In 1916, Ole Kirk Christiansen, who would later found LEGO, bought a Billund furniture company that was founded in 1895. He invested in the town, creating a new dairy and the Skjoldbjerg church. In 1930, Kirk Christiansen began producing utility items such as ironing boards, stepladders and miniature toys. His first toys were created from leftover production scraps but his true toy production started in 1932. In 1934, the toy factory was named "LEGO." A small town, Billund today is most notable as the home of the LEGO Group, for LEGOLAND, and for Billund Airport, the second largest airport in Denmark. The airport opened in 1964 and was built by the LEGO Group, but is now run independently.

Fredericia was designed and built in 1650 by Frederick III as the principal fortress for Jutland. When the city was built, the King gave certain privileges to the city such a freedom of religion and asylum, giving the city a unique diversity (in comparison with the rest of the country) that is still visible today. In 1849 the Danes defeated the Prussians at Fredericia. The fortress was closed in 1909, and the city's modern development began. Fredericia Harbor is among Denmark's busiest and most important harbors. The city has traditionally been famed for the manufacture of refined petroleum, chemicals, textiles, frozen fish, machinery, and tobacco, as well as import from especially Asia and the now closed ship yard.

Taulov, located halfway between Fredericia and Kolding, is the main village of a parish that historically was home to a local vassal, making it the administrative center of the area known as Elbo Herred. Despite recent finds of significant burial mounds and farm houses dating back to the Danish Iron Age, the village itself has little to no significance and was a small railway town with its own municipality until the 1970s, after which it became part of Fredericia Municipality and the arrival of the motorway gave the village a growth spur. The combination of the railroad and motorway has made Taulov an important focal point for the Triangle Region in terms of infrastructure, as the area is unique in having railroad and motorway junctions connecting the area to all of Denmark, Germany and the rest of Scandinavia, and the proximity to one of Denmark's largest harbors and the nearby Billund Airport. The 'Taulov Transport Center' was designated as a 'Core Rail Road Terminal' by the European Union in 2014. The village is also home to various manufacturing facilities such as an Arla Foods export plant and Veksø A/S, a street furniture manufacturing company, and the new 'DanmarkC' area between Taulov and Fredericia is expanding greatly with retail and storage facilities. A new train station is currently being proposed in Taulov to serve as a "Park & Ride"-station for the region when faster train services will be implemented.

Haderslev is situated in a valley, leading from Vojens to Haderslev Fjord and the Baltic Sea. Haderslev was presumably founded by Vikings at least a century before it was granted status as royal borough in 1292. At that time, it had become one of the main trading centres in Southern Jutland. In 1327, Haderslevhus, the royal castle, was mentioned for the first time. It was situated east of the cathedral; an area still called Slotsgrunden. In the following centuries the city prospered, building both the Gothic Cathedral and the second castle of Hansborg (burnt in 1644), which was similar to Kronborg. Due to the plague in Copenhagen, King Christian IV was married there. In the 16th century, the city became one of the first Scandinavian places to embrace the Lutheran Reformation. Prior to the Second Schleswig War of 1864, Haderslev was situated in the Duchy of Schleswig, a Danish fief, so its history is properly included in the contentious history of Schleswig-Holstein. From 1864 it was part of Prussia, and as such part of the North German Confederation, and from 1871 onwards, part of the German Empire. In the 1920 Schleswig Plebiscite that returned Northern Schleswig to Denmark, 38.6% of Haderslev's inhabitants voted for remaining part of Germany and 61.4% voted for the cession to Denmark. It was formerly the capital of the German Kreis Hadersleben and the Danish Haderslev County.