The Chile international has been with the Italian champions for the last two seasons having moved from Serie A rivals Udinese in June 2012.
However, the versatile full-back has struggled to feature regularly at the Juventus Stadium, and caught the eye of potential suitors with his performances at the World Cup in Brazil.
With QPR eager to further strengthen ahead of their return to the top flight, Marotta confirmed a deal had been agreed between the two clubs.
"Tomorrow, Isla will have his medical in England, as a deal has been reached with QPR," the Juve director confirmed on Saturday.
In June, the 26-year-old spoke of his desire to earn a place at Juve this term - with Massimiliano Allegri set for his debut campaign at the club after replacing Antonio Conte.
However, it appears Isla will add further depth to a QPR squad that has already been bolstered by the likes of Rio Ferdinand and Steven Caulker.
