Endrick, who turned 18 last week, arrives from the Brazilian club Palmeiras, where he won two league titles and a Super Cup.
He made his international debut aged 17 against Colombia last November, going on to score his first goal against England in a 1-0 win in March.
He was a member of Brazil’s Copa America squad, making his first international start in the quarter-final with Uruguay which they lost on penalties.
“I don’t have words to describe what I’m feeling because I’ve always wanted to be here,” Endrick said during his presentation at the Bernabeu.
“I wanted to play for Madrid, it’s like a dream coming true today.”
Real Madrid begin the defence of their La Liga title when they face Mallorca on August 18.
© Agence France-Presse
Photo: Cesar Cebolla / Pressinphoto / Icon Sport