Manquillo has represented Atletico Madrid since 2011, but has not turned out for the Spanish giants since the 2013-14 campaign after loan spells at Liverpool, Marseille and Sunderland.
The 23-year-old defender made 20 Premier League appearances during a loan spell at Sunderland last season, but has now made the permanent switch to Newcastle, signing a three-year contract with the Magpies.
Manquillo told Newcastle’s official website: “I’m very happy to be here. From the first moment that Rafa Benitez called me, I just knew that I had to come here, to such a big club. I’m very happy with the challenge ahead.
“I’ve come here to work hard and give everything on and off the pitch. Hopefully then everything will go in the right direction.”
Manquillo has become Newcastle’s fourth summer signing following the arrivals of Christian Atsu , Florian Lejeune and Jacob Murphy.