Konstantin Andreev (1848- 1921) was a Russian mathematician, best known for his work on geometry, especially projective geometry.

He taught at the University of Kharkov from 1873 to 1898. He was one of the founders of the Kharkov Mathematical Society. This society is one of the early mathematics societies in Russia and was founded in 1879.

In 1898 Andreev left Kharkov to take up an appointment in Moscow State University where he was professor of mathematics. He remained in Moscow for the rest of his career and died on 29 October 1921.