The former Real Madrid and Manchester United star, now at Saudi Arabian side Al Nassr, is set to appear at a record sixth World Cup.
Portugal and Ronaldo, the all-time leading men's international goalscorer with 143 goals, have never won the competition.
Ronaldo could face former Barcelona rival Lionel Messi, who is also set to play at a sixth World Cup after leading Argentina to glory four years ago in Qatar.
The Portuguese forward avoided a three-match ban despite being sent off against the Republic of Ireland in their last qualifying match for an elbow.
Spanish coach Martinez selected a 27-man squad with no major surprises, including Ronaldo's Al Nassr teammate Joao Felix.
Paris Saint-Germain stars Vitinha, Joao Neves, Nuno Mendes and Goncalo Ramos are also included, along with Manchester United playmaker Bruno Fernandes and a contingent from Manchester City, including Bernardo Silva.
In the run-up to the tournament, Portugal will face Chile and Nigeria in friendlies before their World Cup campaign begins against DR Congo on June 17th.
Portugal will also face Uzbekistan and Colombia in Group K on June 23rd and 27th, respectively.
Portugal's 27-man World Cup squad:
Goalkeepers: Diogo Costa (Porto), Jose Sa (Wolves), Rui Silva (Sporting), Ricardo Velho (Genclerbirligi)
Defenders: Diogo Dalot (Manchester United), Matheus Nunes, Ruben Dias (Manchester City), Nelson Semedo (Fenerbahce), Joao Cancelo (Barcelona), Nuno Mendes (PSG), Goncalo Inacio (Sporting), Renato Veiga (Villareal), Tomas Araujo (Benfica)
Midfielders: Ruben Neves (Al Hilal), Samu Costa (Mallorca), Joao Neves, Vitinha (PSG), Bruno Fernandes (Manchester United), Bernardo Silva (Manchester City)
Forwards: Cristiano Ronaldo (Al Nassr), Joao Felix (Al Nassr), Francisco Trincao (Sporting), Francisco Conceicao (Juventus), Pedro Neto (Chelsea), Rafael Leao (AC Milan), Goncalo Guedes (Real Sociedad), Goncalo Ramos (PSG)