Pedro III Fajardo de Zúñiga y Requesens (1602 – Palermo, Sicily, 3 November 1647) was a Spanish soldier and noble.
He was born in Mula, region of Murcia, son of Luis II Fajardo, 4th Marquis of Los Vélez, (1576–1631), the preceding Viceroy of Valencia (1628–1631) and a great-grandson of Luis de Zúñiga y Requesens.
Defeated at the Battle of Montjuïc in 1641, and forced to withdraw along the coast to Tarragona, which proved a devastating defeat to Spanish morale, he was dismissed and replaced as Viceroy of Catalonia by Pedro Antonio de Aragón (1642–1644).
He married Ana, a daughter of Fernando Afán de Ribera y Téllez-Girón, 3rd Duke of Alcalá de los Gazules, Viceroy of Naples, deceased 1636.
He remarried with Mariana Engracia Álvarez de Toledo, from the family of the 6th Counts of Oropesa.