Mikel Oyarzabal opened the scoring after two minutes with a fierce strike from the edge of the area before Pedri doubled the lead after the half-hour mark, tapping into an empty net following a cross from Ferran Torres.
Spain added a third early in the second half when Yeremy Pino's delivery forced an error from goalkeeper Pedro Gallese, before Jairo Velez pulled one back for Peru with a low finish.
World Cup fever was evident around the stadium, where Spain shirts dominated the stands alongside Barcelona jerseys, reflecting the club's strong representation in Luis de la Fuente's squad.
Peru supporters were outnumbered but remained vocal throughout the evening.
Pedri, Rodri and Ferran Torres drew some of the loudest cheers as fans broke into chants and performed Mexican waves around the stadium.
World Cup merchandise stalls lined the streets outside, while heavy security protocols did little to dampen the festive atmosphere.
The tournament kicks off on Thursday.