The 41-year-old had reportedly been unhappy with how the club were being run by Saudi Arabia's Public Investment Fund (PIF).
That led to the Saudi Pro League saying "no individual - however significant - determines decisions beyond their own club", and the Portuguese will now return as captain for his side's game at Al-Fateh.
Al-Nassr, third in the table, had teased the news with a social media post showing the captain's armband placed next to Ronaldo's shirt in their dressing room.
Ronaldo moved to the Middle East in December 2022, shortly after his contract with Manchester United was terminated by mutual agreement.
He became the best-paid player in football history with an annual salary of £177m.
However, 10-time league champions Al-Nassr have only won the 2023 Arab Club Champions Cup since he joined.
He signed a new two-year contract last June, but BBC Sport has been told his former Real Madrid team-mate Karim Benzema's recent switch to league leaders Al-Hilal from Al‑Ittihad was the principle reason for five-time Ballon d'Or winner Ronaldo's frustration.
