Reigning European champions Real Madrid have agreed a world-record fee with AS Monaco for the reported fee of €180 million.
According to Madrid-based daily Marca, Real will play Monaco €160 million upfront and further €20 million in the add-ons.
The deal will see Mbappe overtake his France teammate Paul Pogba, who joined Manchester United for €100 million last year, to become the most expensive player in the history of football.
The 18-year-old grabbed headlines last season when he scored 26 goals in 41 appearances for the club in all competitions during his breakthrough season, guiding Monaco to the Ligue 1 title in 17 years and an impressive semi-final run in the Champions League.
Madrid were in the market for striker after Spaniard Alvaro Morata joined Premier League champions Chelsea for €65 million.