Pedro de Valdivia is believed to have been born in Villanueva de la Serena (some say Castuera) in Extremadura, Spain around 1500 (some sources put his date of birth as early as 1497 or as late as 1505) to an impoverished hidalgo family. In 1520 he joined the Spanish army of Charles I and fought in Flanders in 1521 and Italy between 1522 and 1525, participating in the battle of Pavia as part of the troops of the Marquis of Pescara. He reached America in 1535, spent an uneventful year in Venezuela, and then moved on to Peru in 1537.
There he took part on the side of Hernando Pizarro in his struggle against Diego de Almagro and fought in the battle of Las Salinas in 1538, which saw Almagro defeated and captured.:264 Afterwards he accompanied Hernando and Gonzalo Pizarro to conquer both the province of Collao and las Charcas in High Peru (currently Bolivia). As compensation for his help in conquering these lands, he was awarded a silver mine and became a wealthy man.
Valdivia had married Marina Ortíz de Gaete in Spain, but in Peru he became attached to the widow Inés de Suárez, who was to accompany him to Chile as his mistress.