Seppois-le-Bas (French pronunciation: [sɛpwa lə ba] ⓘ; German: Niedersept; Alsatian: Needersept) is a commune in the Haut-Rhin department in Alsace in north-eastern France.

In 1530, the religious authorities and the faithful of a parish comprising the two Seppois, Luffendorf and part of Bisel, signed a charter of 32 decrees, which would be the first of its kind on Alsatian territory.

In 1871, by the Treaty of Frankfurt, Alsace was ceded to the German Empire, with the exception of the southwestern part of the Haut-Rhin which became the Territoire de Belfort.

Although farmers remain largely in the majority, the village also has four restaurants, three carpenters, two bakers, two wheelwrights, two shoemakers, two grocers, two tailors, one butcher, one farrier, one clog maker, one saddler and one cooper.

The village experienced unrest and uncertainty as a result of the First World War: on August 23, 1914 the German army occupied the locality in the morning and the French in the afternoon.

In October 1914, the front stabilized a few kilometers from the village, which became a cantonment for the French army, with the church tower serving as a watchtower.

But faced with the intensification of the shelling, the civilian population was evacuated at the end of January 1916 and did not return until the spring of 1919 to a village transformed into a field of ruins.

During the Second World War, Seppois, like the rest of Alsace, was again annexed to the German Reich, and returned to its status as a border post.