The 18-year-old Portuguese playmaker is one of Europe's biggest prospects, attracting attention from sides in Spain and across Europe.
He has today completed his four-year deal with the 'Hornets', who have the option on an additional 12 months for the attacking midfielder.
Quina was key in Portugal's triumph at the under-19 European Championships and made two appearances in West Ham's 2016/7 Europa League campaign.
9 de agosto de 2018
Watford begin their Premier League season at home to Brighton on Saturday.