The Portuguese has been the club’s third choice keeper for 18 months and impressed with his penalty heroics against AC Milan.
Manchester United’s signing of veteran keeper Lee Grant earlier this month was completed in order to allow for Pereira to receive game time elsewhere.
And according to Portuguese media outlet Record, the keeper will join up with Vitoria, who Mourinho played for between 1983 and 1985.
Vitoria finished 14th in the country’s top division last season and were recommended as Pereria’s next club by Mourinho himself.
The 22-year-old’s last loan move was with Portuguese side Belenenses during the first half of Mourinho’s opening season as Old Trafford, during which he made ten appearances and impressed with a handful of solid performances between the sticks.
He is too good to be playing as a third choice keeper at any club. At his age, minutes on the pitch are more important than anything, and that is exactly what Mourinho will want to see Pereira receive at his former stomping ground over the next nine months.