Katsotas was born in the village of Stamna in Aetolia-Acarnania in 1896. He graduated from the Hellenic Army Academy in 1916 as an Infantry 2nd Lieutenant, and served in the Army until his voluntary retirement in 1929. Following the entry of Greece into World War II in 1940, he was recalled to service, and fought in the Albanian front as a regimental CO with the rank of Lt. Colonel. Following the German invasion of Greece, in April 1941, he fled the country and joined the forces of the Greek government in exile in the Middle East. He assumed command of the 1st Greek Infantry Brigade and fought in the Second Battle of El Alamein.
After the liberation of Greece in 1944, he became Minister of Public Order in the short-lived cabinet of Panagiotis Kanellopoulos (November 1945), and head of the Athens Military Command. He retired again in 1946 and ran successfully for a seat in the Hellenic Parliament in the March 1946 elections, representing his native Aetolia-Acarnania. In 1949, during the last stages of the Greek Civil War, he was again recalled to service and appointed as head of the Central Greece Military Command. He retired in 1950 with the rank of Major General.
Katsotas was again elected to Parliament in the March 1950 elections. He became Minister of the Interior in the cabinet of Sofoklis Venizelos (March–April 1950), and Minister-Governor of Northern Greece in the Nikolaos Plastiras cabinet (May–August 1950).
In 1960, Katsotas founded his own political party, the "Labour-Technical Party" (Εργατοτεχνικό Κόμμα), which in 1961 joined Georgios Papandreou's Centre Union. In February–June 1964, Katsotas served as Minister of Social Welfare in Papandreou's cabinet.
Katsotas was decorated with the Grand Commander of the Order of George I and of the Order of the Phoenix with Swords. He also received the Gold Cross of Valour twice and the War Cross four times.