Beylagan District (Azerbaijani: Beyləqan rayonu) is one of the 67 districts of Azerbaijan. It is located in the centre of the country and belongs to the Mil-Mughan Economic Region. It borders the districts of Fuzuli, Aghjabadi, Zardab, Imishli, and the Ardabil Province of Iran. Its capital and largest city is Beylagan. As of 2020, the district had a population of 99,500.

The name Beylagan historically used in different forms particularly, Paytakaran, Balasakan, Bilgan, Millar and Beylagan. A number of considerations are associated with the toponymy of Beylagan. In accordance with the historical name "Beylagan" derived from the words "pila" (valley) and "gan" (place) and corresponds to the meaning of field or valley.

Another view claims that Beylagan was historically situated on the Barda–Ardabil trade way. Because of that reason, the city became one of the main trade centres in the 9th – 12th centuries. The toponymy "Beylagan" interrelated to that historical base, which means trade way or the place where trading took place. According to the other statements, the toponymy is related to the name of the "bel" tribe who lived there at that time. "Beylagan" thus means the place where "bel" tribes are settled, according to that view.

There is mention of the name of the district in various historical books. One of the "Roads and Countries" is written by Naila Valikhanli. Dimensions of the main historical trade ways are indicated in that book. At the same time, an indication of the route from Greece to Beylagan shows the significance of the city. According to the sources, the north–south line (Derbent – Ardabil road) of the Silk Road passed through Beylagan. Traders of the city built relations with China, India, Iran, Georgia and Byzantium through thanks to this geophysical condition.

In accordance with the historical sources, Beylagan was founded in the 5th century. In the 13th century, the city was completely destroyed by Mongol invasions. Reconstruction of Beylagan started by Amir Teymur in the 14th century but after his death works in that territory stopped. Ancient Beylagan city was ruined in the 16th century and has never been restored again.

Beylagan district was founded on November 24, 1939, and was called Zhanov from 1939 to 1963. In 1963, the Beylagan District was liquidated and merged with the Imishli district. The name of the district was renamed Beylagan with regard to the 1989 dated decree of the Supreme Council of Azerbaijan SSR. The Center of the district is Beylagan city where got city status in 1966.

Beylagan is one of the southwestern districts of Azerbaijan and situated in the Mil valley of the Kur – Araz lowland and in the middle of the Kur and Araz rivers. Geographical coordinates are 39°45’ North latitude and 47°30’ West longitude and bordering Agchabadi, Zardab, Imishli, Fuzuli districts and Iran Islamic Republic in the south-east. Some parts of the Harami plain belong to the district and the northeast part is below the ocean level. More than 40% of the territory is 0 – 100 meters, 25% is 100 – 200 meters and 35% is below 0 meters. Absolute altitude changes between 200 – 250 meters towards Harami plain. Generally, Beylagan is considered a seismic active zone.

The territory is completely plain. Relief is covered by sand, gravel and other sedimentary rocks belong to the Anthropogenic period of the Cenozoic era. 4th-period sedimentary rocks are widespread in the district. At the same time, all sedimentary minerals are found in the territory. There is found gravel, sand in the Harami and Arazboyu plains. Researches reveal that there are a lot of potable water resources in the Harami plain and they are partly used. Furthermore, the territory is used as a pasture.