On top of the enormous fee, Juventus will also pay the 28-year-old £6.3 million ($8.3 million) a season.
The only transfer deals more expensive were Cristiano Ronaldo and Gareth Bale, who cost £80 million ($105 million) and £86 million ($113 million) respectively. Both moved to Real Madrid.
As a striker, Higuain is goal machine. He scored 71 times in just 104 appearances at Napoli and another 30 times for the Argentina national side. He ended the 2015/16 season as the top scorer in Italy's Serie A league.
Before Napoli he also had a six-year stint at Real Madrid, where he scored 107 times.
The transfer is Juventus manager Massimiliano Allegri's fifth signing this summer, after Miralem Pjanic, Dani Alves, Medhi Benatia, and Marko Pjaca.
But a big question is whether Paul Pogba will still be at the club by the time Higuain arrives. Rumours continue in the press that Pogba will move to Manchester United for a record £100 million ($131 million) fee, but reports suggest the deal is being held up because Pogba's agent wants a £25 million ($33 million) cut, which Juventus refuses to pay.