“All the players I have called up come with the hunger to win and make Portugal world champions, Ronaldo included,” said Santos.
Ronaldo will go to his fifth World Cup, having played for his country in every edition of the tournament from 2006 onwards.
The coach, who led Portugal to Euro 2016 glory in France, left Paris Saint-Germain midfielder Renato Sanches out of the squad, bringing Wolves midfielder Matheus Nunes instead.
“What is most important are the players who will go to the World Cup,” said Santos, refusing to discuss players who didn’t make the cut.
“The 26 (selected) think that justice has been done, and those who don’t go, the opposite.”
Santos called up uncapped Benfica centre-back Antonio Silva, 19, as well as 39-year-old Pepe.
The Porto defender has not played since 4 October because of a knee sprain but will be fit for the tournament in Qatar, which starts on 20 November.
“I asked my medical department if there were any unfit players, the answer was no,” said Santos when asked about Pepe.
Liverpool striker Diogo Jota misses out because of a calf injury.
Wolves midfielder Joao Moutinho, 36, who has appeared for his country 146 times, more than any other player apart from Ronaldo, was not included, and nor was his team-mate Goncalo Guedes.
Portugal open their World Cup campaign in Group H against Ghana on 24 November, before facing Uruguay on 28 November and South Korea on 2 December.
Santos was critical of the timing of the tournament, the first ever winter World Cup, but was happy about the lack of travel involved at the tournament, with all the stadiums relatively close together.
“It’s not good for clubs, it’s not good for anyone,” said Santos.
“The exception is that it’s good for travel. I’ve participated in several World Cups and travelling between games was difficult.
“In this aspect, there’s an advantage. No stadium is more than 25 minutes away. We don’t have to walk around carrying everything. It won’t wear us down, the game ends and we go back to the hotel.”
Goalkeepers: Diogo Costa (Porto), Rui Patricio (Roma), Jose Sa (Wolverhampton)
Defenders: Diogo Dalot (Manchester United), Joao Cancelo (Manchester City), Danilo Pereira (Paris Saint-Germain), Pepe (Porto), Ruben Dias (Manchester City), Antonio Silva (Benfica), Nuno Mendes (Paris Saint-Germain), Raphael Guerreiro (Borussia Dortmund)
Midfielders: Ruben Neves (Wolverhampton), Joao Palhinha (Fulham), William Carvalho (Real Betis), Bruno Fernandes (Manchester United), Vitinha (Paris Saint-Germain), Otavio (Porto), Joao Mario (Benfica), Matheus Nunes (Wolverhampton), Bernardo Silva (Manchester City)
Forwards: Rafael Leao (AC Milan), Joao Felix (Atletico Madrid), Ricardo Horta (Braga), Goncalo Ramos (Benfica), Cristiano Ronaldo (Manchester United), Andre Silva (RB Leipzig)