Vázquez did not represent Spain at any youth level.
On 17 May 2016 he, Saúl Ñíguez and Sergio Rico were the three uncapped players named in Vicente del Bosque's provisional squad for UEFA Euro 2016 in France, and he also made it to the final list of 23.
He made his debut on 7 June, starting and playing 61 minutes in a 0–1 friendly loss to Georgia at the Coliseum Alfonso Pérez.

Vázquez appeared once in the tournament, replacing Álvaro Morata in the 70th minute of a 0–2 round-of-16 defeat against Italy at the Stade de France.
He was then included in the final squad for the 2018 FIFA World Cup.
making his debut in the competition on 15 June when he replaced David Silva for the final four minutes of the 3–3 group stage draw to Portugal.
Vázquez did not represent Spain at any youth level. On 17 May 2016 he, Saúl Ñíguez and Sergio Rico were the three uncapped players named in Vicente del Bosque's provisional squad for UEFA Euro 2016 in France, and he also made it to the final list of 23. He made his debut on 7 June, starting and playing 61 minutes in a 0–1 friendly loss to Georgia at the Coliseum Alfonso Pérez.
Vázquez appeared once in the tournament, replacing Álvaro Morata in the 70th minute of a 0–2 round-of-16 defeat against Italy at the Stade de France. He was then included in the final squad for the 2018 FIFA World Cup. making his debut in the competition on 15 June when he replaced David Silva for the final four minutes of the 3–3 group stage draw to Portugal.
Lucas Vázquez