Ronaldo's side was 1-0 down and looked to be on its way to a first defeat in five matches against an Al Batin team sat bottom of the league and with just one win all season.
But Abdulrahman Ghareeb levelled in the 93rd minute, before Mohammed Al Fatil dramatically put Al Nassr ahead in the 12th minute of additional time.
The points were made safe two minutes later, as Ghareeb set up Mohammed Maran to add a third and move Al Nassr to the top of the table.
Despite his team's spectacular comeback, Ronaldo failed to register a goal involvement for the first time in five matches.
It was not for the want of trying though, as the five-time Ballon d'Or winner had a team-high seven shots, though he hit the target just once.
Ronaldo picked up the league's player of the month award before kick-off, after scoring eight goals and adding two assists during February as his team went unbeaten.