Mavromichalis was born in 1797 in Mani and was initiated into the Filiki Etairia in 1818. In the Greek Revolution, he fought against the forces of Dramali Pasha and later, along with Dimitrios Ypsilantis, he commanded the forces that saved Nafplio from Ibrahim Pasha.
When two of his brothers, Tzanis and Petrobey were arrested by government forces under Ioannis Kapodistrias, Konstantinos and the old bey's son Georgios Mavromichalis decided to take revenge. On September 27, 1831 the two Maniots were waiting by the doors of the church St. Spyridonas in central Nafplio. The governor recognised the two men and was worried but before he could do anything they struck: Konstantinos stabbed Kapodistrias through the heart as his nephew shot the governor through the head. As Konstantinos was escaping, he was shot by Kapodistrias' bodyguard, G. Kozonis and was captured by bystanders who mercilessly lynched him while dragging him through the streets of the city. An old General, Christos Fotomaras, heard the commotion and went to his window to find out what was happening. When told by the lynch mob of the murder, Fotomaras pulled out his gun and put Konstantinos out of his misery. The angry citizens of the city then dragged his corpse and threw it off a cliff called the Arvanitis. Georgios Mavromichalis ran into the French Embassy and asked for asylum. His request was refused and he was promptly remanded to the Greek authorities who put him on trial and executed him by a firing squad.