The 22-year-old Spanish left back, who played 77 minutes of The Reds’ friendly at Doncaster last week
, has signed a two-year deal after impressing manager Dougie Freedman during his trial.
Pinillos began his career with local side Racing Santander B and Ourense before moving to second-tier team Cordoba, where he broke into the first team.
Promotion to La Liga followed and Pinillos faced the likes of Real Madrid and Barcelona as he made 12 top-flight appearances.
Following Cordoba’s relegation, Pinillos left the club and will now embark on a new adventure with Forest.