Born in Braga, Sá went from Merelinense to the youth ranks of Benfica in January 2011, and moved six months later to Madeira's Marítimo to finish his development at the age of 18.

[3] On 23 January 2013 he made his professional debut with the B team, playing the full 90 minutes in a 0–0 home draw against Oliveirense in the Segunda Liga championship.

[10][11] Sá made his debut in the UEFA Champions League on 17 October 2017, starting in a 3–2 loss for the group stage away to RB Leipzig and committing a blunder in the eighth minute which resulted in the opposition's first goal.

[24] In September, he provided an assist for Raúl Jiménez against Southampton in their 1–0 win, making him the first Wolves goalkeeper to do so in the Premier League since Wayne Hennessey in October 2009.

[26] On 11 November, despite losing 1–0 to Manchester City, Sá received several praises for his performance, making several vital saves, despite Wolves being reduced to 10 men just before half-time, only failing to defend a penalty.

[32] Sá was first choice at the 2015 UEFA European Under-21 Championship, keeping clean sheets in all games but one as the national side finished in second place in the Czech Republic; in the final, he saved from Sweden's Abdul Khalili in the penalty shootout following a goalless draw at the Eden Arena.

[33][34][35][36] On 25 May 2017, Sá was called to the full side for the first time, being named by manager Fernando Santos in a provisional 24-man squad for that year's FIFA Confederations Cup.

[39] On 16 November 2023, Sá made his debut for Portugal's senior team, starting in a 2–0 away victory over Liechtenstein in a qualifying match for UEFA Euro 2024.