The 22-year-old Spanish left-back, who helped Cordoba win promotion to La Liga in 2014, has signed a two-year deal after impressing manager Dougie Freedman.
Following Cordoba’s relegation in May, Pinillos left the club and has now elected to embark on a new adventure in the Championship with Forest.
He joins fellow new arrivals at the City Ground, goalkeeper Ben Hamer – who has signed on a season-long loan from Leicester – and winger Jamie Ward.
Meanwhile, Radi Majewski and Djamal Abdoun have agreed to terminate their contracts at the City Ground.
Majewski, who joined the club six years ago, said: “I wanted to thank the fans for the amazing support they showed me during my time at Forest.
“It wasn’t easy for me to move to Nottingham from Poland, my first experience of playing football in a new country, but the fans made me feel welcome from the start. This was a huge help to me.”
“I leave the club with many happy memories which I will treasure long after my career is over. I am now looking forward to finding a new club and, hopefully, watching Forest succeed from afar.”
Abdoun arrived from Olympiakos in 2013 and made 27 appearances for the club.