The 22-year-old, who has made five Championship appearances this season, can play as a striker or out wide and has just returned from being part of the Sierra Leone squad at the African Cup of Nations.
Kanu played 17 times and scored twice in League One last season when Peterborough won promotion to the Championship. He only signed a new three-and-a-half-year contract with the club last February, keeping him at London Road until the summer of 2023.
Kanu joined West Ham United's academy as an 11-year-old in 2010 and progressed through the club's youth system before undergoing an unsuccessful trial with Manchester United in 2016.
Kanu then left West Ham to pursue senior football on a regular basis and it was at Aldershot Town in the National League were he caught the attention of then-League One club Peterborough, who signed him at the age of 16.
He has struggled to establish himself as a regular at Posh though, making 69 appearances and scoring 11 goals in four and a half seasons. He has also had loan spells with Boreham Wood and Port Vale.