Reguilòn started 21 games for the outgoing European champions last season including four in the Champions League but had fallen out of favour under the returning Zinedine Zidane who preferred Marcelo in the position.
His situation in the Spanish capital was compounded further by the €55m summer arrival of Ferland Mendy from Lyon, hastening Reguilòn’s loan exit.
“I'm very happy with everything that has happened,” Reguilòn told a press conference while on international duty with Spain, as cited by Marca.
“I am in a great moment and it has been a very strange year for me, going from never being involved in a professional match to representing my national team", he confirmed.