The 20-year-old has been in Valencia's youth setup for the past six years and has made two senior appearances for Los Che.
Mir was previously on the books with Barcelona and Murcia before heading to the Mestalla in 2012, and he has featured regularly for their B team.
According to Super Deporte, Real wanted to sign Mir for their Castilla side to develop him for the future, but Wolves have won the race to sign the Spaniard.
The report states that Wolves will be paying €2m (£1.75m) to sign Mir, handing him a four-year contract to reunite with manager Nuno Espirito Santo, who gave Mir his professional debut at Valencia.
Tottenham Hotspur were also believed to be in the hunt to recruit Mir.