Ronaldo, whose two-year contract makes him the highest-paid footballer in the world, arrived in the Middle East on Monday and completed a medical ahead of his official presentation a day later.
The 37-year-old was greeted by a capacity crowd of 25,000 at a raucous Mrsool Park in Riyadh as excited fans enjoyed an impressive light show ahead of his unveiling.
Speaking at a press conference before walking out onto the pitch in front of his new home supporters, Ronaldo said: “I feel so proud to make this big decision in my life.
“In Europe, my work is done. I won everything and now this is a new challenge.
“I’m grateful Al Nassr have given me this opportunity, not only for the football but for the young generation and the female generation.
“For me, this is a challenge but I feel very happy and very proud.
“I had many opportunities in Europe, in Brazil, in Australia, in the US and even in Portugal many clubs tried to sign me, but I gave my word to this club.
“This is a good chance to grow many important points here with my knowledge and my experience.”
Ronaldo added: “I’m a unique player. I beat all the records in Europe. I want to beat a few records here.
“This contract is unique but I’m a unique player, so for me it’s normal. I really don’t worry about what people say. I am really, really happy to be here.
“I know the league is very competitive, I saw many games. I hope to play after (Wednesday) if the coach thinks there’s a chance. I’m ready to keep playing football.”
Ronaldo, who has a reported salary of over £160m per year, could make his debut on Thursday against Saudi Pro-League side Al Ta’ee or on Saturday against Al Shabab.