At the time of the death of Viceroy Gaspar de Zúñiga y Acevedo, Count of Monterrey in late 1606, Núñez de Avendaño was president of the Audiencia of Lima. In virtue of his position he became acting viceroy of Peru, but died early in 1607.
The death of Viceroy Gaspar de Zúñiga y Acevedo led to Núñez de Avendaño becoming acting viceroy of Peru. He held this position until his own death in 1607.