The first effective Spanish viceroy of Naples, in 1532–1552, he was responsible for considerable social, economic and urban improval in the city and southern Italian kingdom in general.

Don Pedro also built the viceregal palace as well as a dozen blocks of barracks nearby, a square grid of streets lined with multi-storied buildings—unique in Europe for its time.

He instituted summary execution for petty theft on public streets and made it a capital crime to go armed at night in the city.

He was ruthless in dealing with feudal barons in the countryside and encouraged their moving into the city within reach of a central authority.

Additionally his Jewish chief financier Samuel Abravanel along with his wife Benvenida, may have had some influence on him, in regards to ending his aspirations of an Inquisition.

[3] Don Pedro Álvarez de Toledo married in 1508 Maria Osorio y Pimentel, 2nd Marchioness of Villafranca del Bierzo.