The 22-year-old is expected to pass his medicals today and sign a deal worth £4.5m though the London side was asking for £5.5 million to let the winger leave.
Osayi only has one year left on his contract at the Kiyan Prince Foundation Stadium, and is seemingly edging closer towards an exit.
He scored five goals and provided nine assists in 37 appearances for the London side last season in the championship.
The winger will have the chance to play Champions league football with the Belgian side next season if everything goes well.
Osayi-Samuel left Nigeria with his family for Spain at a tender age but later moved to England at the age of 10.
He started his professional career at Blackpool in March 2015 and he spent two years at the club before switching to QPR in 2017.