Santos was part of the Portuguese squad at the 2015 FIFA U-20 World Cup, scoring an early goal against Senegal (3–0) and a late one against Colombia (3–1 win) in the group stage, in an eventual quarter-final exit in New Zealand. He won the first of his two caps for the under-21 side on 12 November of that year, replacing Rony Lopes midway through the second half of the 4–0 victory over Albania for the 2017 UEFA European Championship qualifiers held in Arouca.