The 37-year-old will earn an eye watering £175million-a-year.
Ronaldo left Manchester United in November after his contract was terminated with six months left on it.
The five-time Ballon d’Or winner is now set to continue his career in the Middle East.
According to Marca, Ronaldo’s deal is for seven years and he will play for two-and-a-half years before taking up an ambassadorial role.
His decision to move to Saudi Arabia effectively ends his career at the top level. It is thought Ronaldo had been hoping to secure a switch to a Champions League club but it never materialised.
Part of his role as an ambassador will be to help Saudi Arabia’s joint bid with Egypt and Greece to host the 2030 World Cup, it has been claimed.