Russo, 62, has been convicted of murder and for association with the mafia in absentia and sentenced to life in prison 13 times.
He was arrested at a farmhouse near the town of Sperone with another of his brothers, Carmine Russo, 47, who had also been on the run since 2007.
Salvatore Russo, 51, had been arrested on Saturday at a farm near Naples, after escaping capture for 14 years.
The Russo clan, based near the town of Nola, is a key player in the organised crime syndicate that operates in and around Naples, called the Camorra.
The Naples Camorra is made up of several dozen families and is thought to have 5,000 members.