The centre-back, 24, could make his debut against Manchester United in the Clarets' first Premier League home fixture tomorrow.
Royals director of football Nick Hammond said: "Andre stayed with us last summer to help us get back into the Premier League, but this time around he was desperate to play at that level.
"He felt it was crucial with regards to his World Cup ambitions and also the African Cup Of Nations, for which he will be away in January.
"Andre is a great lad, and I am sure the fans will miss him because he gave us some great moments.
"Like all of our departing players, we wish him every success for the future."
Due to a technicality, the Cameroon international's four-match ban - imposed after his sending-off against Burnley in last season's Championship play-off semi-final first leg - will be completed tonight when Reading play Swansea.