Xuanwumen was located on western section of the southern wall. It was built in 1419 when Beijing's southern walls were expanded. Before the Zhengtong era (1435–1449) the gate was called Shunchengmen, while commoners referred to it as Shunzhimen. The gate tower was completely rebuilt during the Zhengtong era, and a barbican, sluice gate tower, and watchtower were added. The name was changed to Xuanwu ("martial announcement"), from a quotation from Zhang Heng's Dongjing Fu: "the martial etiquette is to announce 武节是宣 wu jie shi xuan". The gate tower was five rooms wide and three deep, with an overall width of 32.6 metres and a depth of 23 metres. The gate tower had two levels and was 33 metres high. The roof was built in the multi-eaved Xieshanding style with green glazed tile edges on grey tiles. The watchtower was similar to the one at Zhengyangmen, but on a slightly smaller scale. The barbican was 75 metres wide and 83 metres deep, with sluice gates on the eastern and western sides and one archway on each side. A Guandi Temple was located on the northwestern corner of the barbican, facing southward. The watchtower was dismantled in 1927. The watchtower platform and the barbican were dismantled in 1930, and the gate tower was dismantled in 1965. The giant cannons on Xuanwumen were fired at noon.

Xuanwumen was informally referred to as the "Death Gate", because carts carrying prisoners for execution were taken through this gate to the execution ground, located in Caishikou, to the south. Beijing's many cemeteries were located in and around Taoranting in the southern suburbs. Funeral carts carrying commoners would often leave the city through Xuanwumen.

Of the nine Inner city gates of Beijing, Xuanwumen was built at the lowest elevation. Although normally the river system accommodated and directed water flow out of the city through Zhengyangmen's eastern sluice gates, these proved ineffective during heavy rainstorms, when most of the water would flood out of Xuanwumen. According to Guangxu Shuntianfu Zhi, heavy rainstorms in Beijing in 1695 flooded the gates at Xuanwumen, making them impossible to open. Six elephants were brought over from the zoo to force open the gates, and the flood finally dissipated out of the city.