It flows generally east and southeast about 95 km (59 mi)[3] to join the Stikine River at Tahltan, British Columbia.

[5] The Tahltan River's watershed covers 1,851 km2 (715 sq mi),[4] and its mean annual discharge is 21.5 m3/s (760 cu ft/s).

It first flows south and southeast then east and northeast, gathering many unnamed tributary streams.

Decheeka Falls, located about 3 km (1.9 mi) upstream of the Little Tahltan confluence, sometimes acts as a barrier to fish migration.

In 2018 large scale remediation efforts were completed, widening the river's channel and distributing rock debris downstream.