Madrid completed a 45-million-euro ($50.3 million) deal for Rodrygo Silva de Goes in June last year but agreed to let the Brazilian striker stay at Santos for another season.
He is the fifth players to join Madrid this summer, following Eden Hazard, Eder Militao, Ferland Mendy and Luka Jovic for a minimum transfer outlay to 300 million euros.
'Hazard could be catalyst for new Real Madrid chapter'
"For me it is a dream come true," Rodrygo said at a press conference. "I have always said it is the dream of every child in Brazil and the world. I'm living a dream, it's the happiest day of my life."
Rodrygo has signed for Madrid's first team but said he would be happy to play for Castilla, the club's B side, to gain experience.
After being presented in the stands by club president Florentino Perez, Rodrygo emerged on the pitch at the Santiago Bernabeu, where he kicked balls into a crowd of around 2,000 fans.
"I'm a fast striker, I score and dribble," he said. "I'm Brazilian and we're a bit like that, like Robinho and Neymar, I identify a little with them.
"I like to play on the wings, on the left especially, but I have no preference. I'm ready to play."
Neymar has been linked with a return to Spain, just two years after he joined Paris Saint-Germain from Barcelona for a world record 222 million euros.
Asked if he would like either to play alongside or emulate his compatriot, Rodrygo said: "Neymar is a great player but he's on another team and I can't talk about him.
"No, I would like to be the Rodrygo of Madrid. There is only one Neymar, there can't be another."
Madrid struggled for goals last season in the wake of Cristiano Ronaldo's departure to Juventus, despite another Brazilian teenager, Vinicius Junior, enjoying an impressive first year in the Spanish capital.
Vinicius began the season playing for Castilla but was promoted by coach Santiago Solari. Rodrygo hopes to follow suit.
"I have spoken to Vincius since I signed and when we met in the national team we talked about the club," Rodrygo said.
"Madrid always has the best players in the world, I know there will be a lot of competition but I am available to the club to play in the first team or for Castilla.
Real Madrid sign Mendy to continue summer spree
"The pressure is there at all football clubs but here it is much higher. Vinicius told me about his experience. He told me to be patient. I'm young, I have a big future ahead of me and everything will happen naturally."
Perez said: "Today marks a momentous time in your career, soon you will wear the white shirt.
"Your growth has been spectacular and you now face the challenge that you have chosen. Here you will succeed with work and humility, the fans will always be on your side but you must know the high demands of our club, it is a hallmark of Real Madrid."
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ