The 20-year-old striker spent last season on loan at Barreirense.
Tomane has signed a four-year contract at El Madrigal but it is believed he could be loaned out to another Spanish team.
Tomane said: “Villarreal is a big club in Spain and the perfect place to progress as a player.
“For me this will be a sensational adventure and I am hoping to get in the first team soon.”
