There had been huge doubt over the forward's international future following the 2022 World Cup, but incoming head coach Roberto Martinez made it clear that Ronaldo was very much in his plans.
At 39, he has scored 42 times and registered 13 assists in 42 appearances for Al-Nassr this season, and Ronaldo is now preparing to feature at a record sixth European Championship.
Portugal will open their Euro 2024 challenge with a clash against Czech Republic on June 18, while they will also take on Turkey and Georgia in the group stage of the competition.
Ronaldo has scored a staggering 128 goals in 206 appearances for Portugal since making his debut in August 2003, and he is set to be an important player for Martinez's side at Euro 2024.
Ronaldo will again spearhead Portugal's challenge
There are nine Premier League players in the group, including Ruben Dias and Bernardo Silva, who helped Manchester City win the English title this season.
Meanwhile, Manchester United duo Diogo Dalot and Bruno Fernandes are also in the squad.
Pepe is selected at the age of 41, with the defender the oldest player in the group, while Benfica's Joao Neves, who is being heavily linked with a summer move to Man United, is the youngest at the age of 19.
"Pepe's role in the locker room is important, the way he represents the national team shirt," Martinez told reporters during his press conference.
"When he is fit, he is a very important player. We have a very interesting dressing room because we have players from different generations.
Nine Premier League players are in the squad
"We have a good mix of experience and youngsters. It's a list of 26 players that will give a good response."
Joao Felix, who has spent this season on loan at Barcelona from Atletico Madrid, is also named in the squad, as is Wolverhampton Wanderers' Pedro Neto, with the attacker recently back from injury.
Alongside Ronaldo, there are two further players from the Saudi Pro League in the squad, with Al-Nassr's Otavio and Al-Hilal's Ruben Neves selected.
"Decisions have to do with the level at which the players are at," Martinez added. "The level of competition is not a problem, it is more a question of the number of minutes, games, personal moment and role in the national team."
Man City's Matheus Nunes is a notable absentee from the squad, with the midfielder overlooked for a position, while Bayern Munich's Raphael Guerreiro misses out through injury.
Portugal Euro 2024 squad in full:
Goalkeepers: Diogo Costa (Porto), Jose Sa (Wolves), Rui Patricio (AS Roma)
Defenders: Antonio Silva (Benfica), Danilo Pereira (Paris Saint-Germain), Diogo Dalot (Manchester United), Goncalo Inacio (Sporting Lisbon), Joao Cancelo (Barcelona), Nelson Semedo (Wolves), Nuno Mendes (Paris Saint-Germain), Pepe (Porto), Ruben Dias (Manchester City)
Midfielders: Bruno Fernandes (Manchester United), Joao Neves (Benfica), Joao Palhinha (Fulham), Otavio Monteiro (Al-Nassr), Ruben Neves (Al-Hilal), Vitinha (Paris Saint-Germain)
Forwards: Bernardo Silva (Manchester City), Cristiano Ronaldo (Al-Nassr), Diogo Jota (Liverpool), Francisco Conceicao (Porto), Goncalo Ramos (Paris Saint-Germain), Joao Felix (Barcelona), Pedro Neto (Wolves), Rafael Leao (AC Milan)