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.