The Portugal captain, who moved to Saudi Arabia on a free transfer after his Manchester United contract was cancelled by mutual consent, opened his account with a late penalty at Prince Abdullah bin Jalawi Sports City Stadium.
Saudi Pro League leader Al Nassr twice came from behind to secure a point on the road.
Ronaldo got up and running in his third game for his new club to deny sixth-placed Al Fateh.
The 37-year-old forward calmly dispatched his spot-kick in the 92nd minute before his team-mate Talisca, who scored Al Nassr's first goal to cancel out Cristian Tello's opener, was sent off in a dramatic finale.
Ronaldo had scored twice for Riyadh All-Stars in a 5-4 friendly draw against a Paris Saint-Germain side that included Lionel Messi and Kylian Mbappe last month.