Thiago Alcantara has dual citizenship, holding both Brazilian and Spanish citizenship. Alcantara is multilingual, speaking five languages fluently: Spanish, Portuguese, German, Catalan, and English.

Alcantara was eligible to represent Brazil, Italy, and Spain because he is Brazilian, was born in Italy, and grew up in Spain. Alcantara ultimately chose Spain. Thiago represented Spain in the 2008 UEFA European Under-17 Championship, assisting his country to a tournament victory and scoring in the final.

Alcantara was a constant in Spain’s successful 2011 UEFA European Under-21 Championship campaign, scoring the second goal of a 2–0 victory over Switzerland with a 40-yard free-kick. Alcantara was named the final’s man of the match.

On August 10, 2011, Thiago made his senior squad debut in a friendly against Italy, and his first competitive match was on September 6, 2011, in a 6–0 win over Liechtenstein in a Euro 2012 qualifying match. Thiago missed Euro 2012 and the London Summer Olympics 2012 due to injury.

On May 13, 2014, Alcantara was named to Spain’s 30-man provisional squad for the 2014 World Cup.