After the victory of Antonio Rastrelli, Martusciello entered the regional council, and held the position of head deputy of Forza Italia until the elections in 1999.

Martusciello's fourth regional appointment was to the newly formed People of Freedom party, and was unanimously elected president.

Starting on 20 October 2012 Martusciello acted as an Advisor to the President of the Campania Region, with the express responsibility of handling economic and developmental matters.

In December 2012, Martusciello was under investigation by the prosecutor's office of the Republic of Naples due to irregularities in costs to the Regional Director.

In July 2015, Martusciello became a suspect for making agreements with the Mafia as part of the request for the distribution of contracts for the maintenance of the water network in Campania from the farms associated with the Casalesi clan.

In 2018, Martusciello caused controversy when he joined Ryszard Czarnecki for an unauthorized trip to Bangladesh, where they met with Prime Minister Sheikh Hasina.