The Portugal forward, 38, scored his sixth league goal in four games, while former Liverpool forward Sadio Mane was also on the scoresheet on Saturday.
Ronaldo has scored 26 goals in 30 games since joining from Manchester United in December.
He scored his 800th career goal in December 2021 at United.
Ronaldo, who has scored a record 123 men’s international goals, posted on social media after Saturday’s game: “Another great team performance! We keep improving. 850 career goals and still counting.”
The victory puts Al-Nassr four points off Al-Hilal in first.
Aleksander Mitrovic’s hat-trick meant the league leaders won 4-3 at Al-Ittihad on Friday, with Karim Benzema scoring for the hosts.
Meanwhile, Moussa Dembele’s double helped Al-Ettifaq to a 3-1 win over Damac.
Victory for Al-Nassr extends their unbeaten run to four matches, while the win for Steven Gerrard’s Al-Ettifaq ended a two-match winless run.
Elsewhere, an Al-Ahli side including Roberto Firmino, Gabri Veiga, Riyad Mahrez and Allan Saint-Maximin were beaten 5-1 by Al-Fateh, causing them to lose ground at the top.
