The 22-year-old winger was one of the rare bright spots at Real Valladolid last season. As the Pucelanos were relegated from LaLiga, Moro registered four goals and five assists in 33 league games. At the recent U21 Euros, Moro provided two assists in four games for Spain.
"It's no secret that we've been fond of this player for quite some time and have been in contact with him for a while. That's why we're very pleased to have been able to officially welcome Raúl to Amsterdam," said Ajax director Alex Kroes.
"Despite strong interest from other clubs, he believes in the sporting vision we've laid out. He's quick, technically skilled, capable of playing on both flanks, and able to beat his opponent both on the inside and the outside. I’m convinced he’s going to bring us a lot of joy."
The small-framed Moro, who stands at a height of 1.69m, signs a five-year deal at Ajax, who reportedly paid around €10 million for the youth international. The fee could rise to €11.5 million due to several bonuses.
The Amsterdam giants were on the verge of signing him in January when a shoulder injury prevented the move for the Spanish youngster.
Moro joins a group of forwards that includes former Chelsea man Bertrand Traore, Steven Berghuis, and the up-and-coming Rayane Bounida.