The Bianconeri director said the midfielder will extend his contract shortly, and has also stressed Paul Pogba is going nowhere.
The Scudetto holders have been in talks with the Chile international for a while now and Marotta revealed that it's only a matter of time before Vidal will extend his current contract, which is due to expire in the summer of 2016.
"We have reached the final stages of the renewal talks with Vidal. We will make things official next week," Marotta told Sky Sports.
The 26-year-old has been in superb form for Juventus so far this season, scoring 10 goals in 20 appearances in all competitions. Marotta also had his say on the future of Paul Pogba, who has recently been linked with a move to Paris Saint-Germain, and stressed that there have been no offers for the France international.
"Pogba has been doing a fine job," Marotta said. "But there is no concrete interest in him that needs his attention."
Pogba, 20, has a contract with Juve until June 2016.