He became an officer in the Hellenic Army, fighting in the Greco-Turkish War of 1897, the Balkan Wars, World War I (as Lieutenant Colonel) and later in the Asia Minor Campaign, reaching the rank of Lieutenant General. After retirement, he entered politics, serving as Interior Minister in 1922–1923 and Minister for Military Affairs in 1924. He was subsequently elected into the Greek Senate in 1929.
Periklis Pierrakos-Mavromichalis also competed at the 1896 Summer Olympics in Athens.
In the preliminary round, he went 2-1 in his group. He lost to Henri Callot, the eventual silver medallist, but defeated Henri Delaborde and Ioannis Poulos to finish second in the group.
There was no match between him and Athanasios Vouros, who had placed second in the other group. Pierrakos-Mavromichalis was awarded third place because his record of 2-1 in matches was better than Vouros"s 1-1.