The Kovzha (Ковжа) is a river in the Vytegorsky, Belozersky, and Vashkinsky districts of Vologda Oblast in Russia.

The source of the Kovzha is in the western bay of Lake Kovzhskoye.

The river follows about 10 kilometres (6.2 mi) its natural course and then joins the Volga–Baltic Waterway and turns south.

In the lower course, the Kovzha forms the border between Belozersky and Vashkinsky Districts.

Between 1927 and 1959 the selo of Annensky Most, in the middle stream of the Kovzha, was the administrative center of Kovzhinsky District.