Walcott has yet to feature for the Gunners this season due to a back problem.
The 20-year-old returned to training last week and played 60 minutes of a practice game against an Olympiakos Under 20s side on Monday.
“We played against Olympiakos Under-20s and he [Walcott] played for 60 minutes and came through well,” said Wenger.
“He will be available for England selection and for us on Sunday.”
