Sampson was born in the Cypriot port city of Famagusta to Sampson Georgiadis and Theano Liasidou. During his teenage years, he was a promising right back in the second team of Anorthosis Famagusta football club. The man who once boasted "Nobody says "no" to Nicos!" began his working life at a Nicosia newspaper, The Times of Cyprus, which was owned by Charles Foley. His original name was Nikos Georgiadis, but he adopted his father's forename as his (public) surname, a common custom in Cyprus in those days. Less well known as a Greek surname, it has been surmised that Sampson referred to the biblical figure, or even borrowed a chip off the English block. It helped to distinguish him from others who bore his surname and it was his nom de guerre during the EOKA resistance campaign against British rule in Cyprus, waged from 1955 to 1959, although he also became known as Atrotos (Greek: Áτρωτος), or Invulnerable.
"Nicos Sampson carries a Turkish flag captured during his attack on Ormophita, a Nicosia suburb. His militia and those of other Greek Cypriot ministers led to a near civil war when the Turkish Cypriots responded in kind in late December 1963. The Greek press reported 'what is taken after bloodshed is not given back'."In Greece, Turkey and Cyprus, the 1950s were marked by a rise in nationalistic fervour. Since its inception in 1955, the EOKA organisation actively recruited young patriots during the period of its struggle. Joining EOKA, the young Sampson became known to the British Army and police as one of EOKA's most feared resistance fighters. He participated in a number of killings carried out along Ledra Street, including three police sergeants, for one of which Sampson was tried in May 1957. He confessed but was acquitted on the grounds that his confession may have been coerced by torture. By March 1959, when the shooting ended, 509 people had died, of whom 156 were British soldiers and police.
In 1960 he set up the newspaper Makhi, meaning battle, or struggle, which was one of the first Greek newspapers in circulation in the nation of Cyprus. In 1961, in a series of newspaper articles, he admitted his responsibility for the death of the police officers in 1956 during the resistance campaign against British rule. According to the Telegraph, as a journalist, he flew to Algeria to interview Ben Bella and to Washington to talk to J F Kennedy. He quickly accumulated race horses and fast cars from Greek and Greek Cypriot businessmen eager to show their patriotism.
Following an explosion to the statue of EOKA hero Markos Drakos in Nicosia, Sampson actively participated in clashes between the Greek and Turkish communities in December 1963. On the morning of 24 December, the clashes in Nicosia spread and fighting continued into the subsequent year. The fiercest fighting took place in Constantia, Neapolis, Ledra Palace and, especially, the suburb of Omorphita (Kucuk Kaymakli) where Sampson was particularly active. In Omorfita, which had a majority Turkish Cypriot population, Sampson led armed groups in fierce battles between Greek Cypriot and Turkish Cypriot irregulars after the Greek Cypriot families living in the suburb came under heavy fire from Turkish Cypriot militias who were aiming at bringing the whole suburb under Turkish Cypriot control. Apart from conventional weapons his groups used excavator trucks as makeshift tanks. According to American sources there were 17 dead, most of them Turkish Cypriots, and 70 wounded. In total, it is estimated that the whole intercommunal war cost the lives of about 350 Turkish Cypriot and 200 Greek Cypriot. The result of these clashes was the departure of the Turkish Cypriots from government and the segregation of the Turkish Cypriot community into enclaves. The United Nations responded by dispatching a peacekeeping force to Cyprus. The precise nature of the role of these troops, mostly British troops, has been the subject of some controversy.
On May 10, 2001, he died in Nicosia.