Estupinan is on board for five seasons after moving from Villarreal.
He will aim to impress in his new surroundings and arrive at the World Cup in great form.
The 24-year-old will help cover the void left by the departure of versatile Marc Cucurella to Chelsea.
Albion boss Graham Potter said: “We’re excited by what Pervis brings us and he fills a position to which we’ve been looking to add depth.
“In addition to his international experience, he has played for Villarreal in the Champions League and Europa League, as well as gaining plenty of experience in LaLiga.
“We will help him to settle here in England, but we’re looking forward to working with him and seeing him in action in the Premier League.”
The national team’s Twitter account @LaTri wished Estupinan “success in this new stage” of his career.