Ronaldo, who signed for the Riyadh club in December before scoring 14 goals in 16 league games, picked up a muscle injury four days earlier and was rested ahead of Portugal's European Championship qualifiers against Bosnia-Herzegovina and Iceland in June.
In the 38-year-old Ronaldo's absence, Anderson Talisca took center stage to score twice. He also assisted Mohammed Marwan for a third.
Al-Ittihad, who had already secured the league championship in the penultimate round, celebrated a first title since 2009 with a 2-0 win against Al-Tai.
Abderazzak Hamdallah of Morocco opened the scoring with a second-half penalty that also secured the golden boot with his 21st goal of the season. Former Leeds United and Wolverhampton winger Helder Costa added the second in injury time.
Al-Hilal, champions last season, finished in third spot with a 3-2 win over Al-Raed .
The league will expand from 16 to 18 teams next season.