It can be used to plate metals with copper, as a fungicide or herbicide,or as a chemical test for water (the anhydrous form will absorb water, turning blue). Mixed with lime it is called Bordeaux mixture. It is also used, in Fehling's solution, to test for reducing sugars, which reduce the blue Cu2+aq ions to red copper(I) oxide. Still other uses include hair dyes and the processing of leather and textiles.

Copper sulfate is also used to test blood for anemia. A drop of the patient's blood is dropped into a container of copper sulfate, if it sinks within a certain time, then the patient has sufficient haemogloblin levels and is not anemic. If the blood floats or sinks too slowly, then the patient is iron-deficient and may be anemic.

In a flame test, copper ions emit a deep blue-green light, much more blue than the flame test for barium.