Ronaldo said he dreamed of playing for Real Madrid but had never been to the legendary Madrid stadium before Monday night.
"I am very happy to be here," Ronaldo, clad in Real's all-white strip and his new number nine shirt, said. "A childhood dream has come true for me, to come to Real Madrid. It's incredible that the stadium is full just for me," he added, before showing off his skills with the ball and greeting fans.
Ronaldo is the most expensive signing in a $300 million spending spree by Florentino Perez, who is beginning his second reign as Real Madrid president.
Also signed were Brazilian midfielder Kaka, French striker Karim Benzema and Spanish defender Raul Albiol.
Perez's first term was highlighted by the signing of "Galacticos" David Beckham, Zinedine Zidane and Luis Figo.