Ronaldo has scored 14 goals in 16 league games since making his debut in January, but could not get a winner this time and Gustavo had a second-half strike ruled out for offside with 10 minutes remaining.
Al-Ittihad won easily thanks to two goals from Brazilian forward Romarinho as well as a third-minute strike from Ahmed Sharahili. The team, which is led by former Wolverhampton and Tottenham manager Nuno Espirito Santo, secured its ninth league title overall.
"I want to thank the players and the fans for their support this season and everyone has worked very hard from the beginning," Santo said. "The early goal was very important and after we scored then we settled down."
Defending champion Al-Hilal moved into third place with a 3-0 win at Abha.