The name Perez comes from the Hebrew personal name פרץ (perets, pronounced pe-REHTZ), where it is the name of the older son of Judah and Tamar mentioned in Genesis 38:29. The name is based on the Hebrew noun of the same spelling, פרץ (perets), meaning "a breach, gap," and the corresponding verb, פרץ (parats, pronounced pa-RAHTZ), meaning "to breach, burst forth." The etymology given for the child in Genesis 38:29 highlights this verbal link: "And she said, 'What a breach (פרץ) you have made (פרצת, literally: "breached") for yourself!' Therefore he was named Perez (פרץ)."

The name Perez is also quite common in Castilian Spanish, where the name means "son of Pedro/Peter." However, the Spanish and Hebrew etymologies are unrelated, as the Castilian Bible transliterates the name in Genesis 38:29 as "Farés." Still, it became an incredibly popular name among Sephardic Jewish communities, most likely because of this ambiguity, and is one of the more popular surnames in modern Israel.