The teenage sensation has put pen to paper on a contract extension which will come to an end in June 2022.
The contract is seen as a logical step in the career of the 17 year old who has taken the league by storm.
"As a young player you can't be better than at Anderlecht," Doku claims after agreeing to the extension.
He added: “Here you get the chance to gain experience at the highest level. Every day I learn something from experienced coaches and players with an impressive career such as Vincent Kompany and Nacer Chadli. This is a well-considered and logical step in my still young career".
Sports Director of Anderlecht, Michael Verschueren hails Doku as an example of all talents in the club.
“At Anderlecht, every young player can patiently build a great career. With this decision he follows in the footsteps of Romelu Lukaku, Leander Dendoncker, Dennis Praet, Youri Tielemans and many other talents who have taken the right steps to be where they are today”.