The transfer of Akram Afif was confirmed on Sunday by Qatari club Al Sadd, where former Barcelona midfielder Xavi plays.
Having a Qatari national appear in one of Europe's strongest leagues is seen as a boon for the Gulf country that has spent millions of dollars developing young players as it prepares to host the 2022 World Cup.
"I hope I can be one of the best players in La Liga for Villarreal ... playing in the Champions League is an objective for me," Afif told Qatar's World Cup organising body in an interview.
"I also hope more Qatari players can play in Europe ... to learn a lot of things for the World Cup. The World Cup is in our country and it is a big chance for Qatari players."
Doha-born Afif had been on loan since 2015 to a Qatari-owned team in Belgium's second division, Kas Eupen, where he scored six goals in 16 appearances.
He is a product of Qatar's Aspire Academy, which has spent millions of dollars nurturing Qatari footballers as well as naturalised foreign talent.
One of only a handful of Qatari players to play in Europe, Akram made his debut for Qatar's national team last year during a 15-0 win over Bhutan in a World Cup qualifier.
(Reporting by Tom Finn, editing by Nick Mulvenney)
