Barritt started last weekend's 42-20 Aviva Premiership victory over London Irish at Twickenham, but was omitted from the matchday 23 for Sunday's clash with Gloucester.
The 27-year-old has had corrective surgery on damaged ligaments in his foot and is expected to return by Christmas.
"Brad is a tremendously important player for us and for England," Saracens director Mark McCall said.
"He will be missed through the autumn, although we have talented players ready to step forward.
"Brad is on the road to recovery and we look forward to his return later this season."
- Sports & Recreation
- Aviva Premiership