Chelsea have signed Brazil playmaker Oscar from Internacional in a deal worth a reported STG25 million ($A38.15 million).
The Champions league winners announced the move on their website on Wednesday without revealing the length of the deal or fee.
The 20-year-old player, whose full name is Oscar dos Santos Emboaba Junior, is currently with the Brazilian squad for the London Olympics and will join up with Chelsea after the football tournament.
Oscar made his debut for the senior Brazil team as a substitute in a 0-0 draw with Argentina last September. He has one goal in his six internationals.
Oscar is a product of the Sao Paulo youth academy and joined Internacional in December 2010. He has played at every level of international football from under-15 onward with Brazil.