A statement released by Niger's defense ministry said clashes between armed forces and "terrorist elements" broke out between Sunday and Monday in western Tillaberi region near Burkina Faso.
18 soldiers were also injured, added the statement.
Tillaberi is in the vast and unstable "three borders" region between Niger, Mali and Burkina Faso, where jihadist insurgents have carried out attacks for years.
The latest fighting, which erupted in an area northwest of the town of Tera, follows several other deadly attacks in the region in recent weeks.
At the start of the month, Niger held three days of national mourning after 29 soldiers were killed in a suspected jihadist attack, the deadliest since the military took power in July.
Niamey is battling two jihadist insurgencies — a spillover in its southeast from a long-running conflict in neighboring Nigeria, and an offensive in the west by militants crossing from Mali and Burkina Faso.
The West African nation's military rulers on July 26, overthrew democratically elected president Mohamed Bazoum, citing the deterioration of the security situation in country as justification.