Alfieri was born in Saviano, near Naples. The Camorra entered in his life when he was only seven. In 1953, he took an oath with his brother Salvatore, to avenge the killing of their father Antonio Alfieri. Three years later, in 1956, Salvatore Alfieri killed the murderer of his father. In the 1960s Carmine was first arrested. In 1974, he was initiated in the Camorra as uomo d'onore (man of honour). In 1978 he was charged for homicide and in 1981 for mafia association.
In the 1980s he was among the founders of the Nuova Famiglia, which was opposed to the then dominant Nuova Camorra Organizzata of Raffaele Cutolo. The rivalry caused a ferocious war with a huge number of victims, including Carmine’s brother Salvatore. The Alfieri clan of the 1980s and 1990s exhibited a hubris and a penchant for wanton violence that compared favorably with Cosa Nostra’s spectacular assassinations. According to police estimates, Alfieri’s killers alone counted as many as 500 murders during the decade 1983-93. For instance, Domenico Cuomo, Alfieri's main hitman confessed to have committed over 90 murders within the same period.
Cutolo overplayed his hand in the Cirillo kidnap affair. His former political protectors turned and provided their support to Carmine Alfieri, his main rival in the bloody 1981-83 Camorra war between Cutolo’s Nuova Camorra Organizzata (NCO) and the Nuova Famiglia. In November 1982, the NCO's financier, Alfonso Ferrara Rosanova, was murdered. When Cutolo’s deputy and main ‘military’ chief, Vincenzo Casillo was killed via a car bomb in January 1983 by the allies of Alfieri, it was clear Cutolo not only had lost his political protection but the war as well. Many other Camorra gangs understood the shift in the balance of power caused by the death of Casillo. They abandoned the NCO and allied themselves with Alfieri.
After the defeat of Cutolo, war broke out among the anti-NCO coalition, in particular between the Nuvoletta clan from Marano and Antonio Bardellino at the end of 1983. Alfieri sided with Bardellino’s Casalesi clan. The war culminated in the Torre Annunziata massacre of August 1984, which left eight people killed and 24 wounded among the Gionta clan allied with Nuvoletta. After the massacre and the murder of Ciro Nuvoletta two months earlier, the balance of power shifted in favour of Alfieri.
In the first instance Alfieri and others were convicted for having organised the massacre and given life sentences. However, on appeal they were acquitted thanks to the intervention of politicians and the help of judge Armando Cono Lancuba.