The England international has been on the sidelines since January after suffering knee ligament damage, which required surgery.
As a result, the 25-year-old missed the Three Lions' World Cup campaign in Brazil, and is expected to be absent for the start of the Gunners' 2014-15 season.
"He's progressing very well," Wenger told the club's official website. "He's worked very hard during the summer and we expect him to be back in full training at the end of August.
"[It's] difficult to predict [when Walcott will return to the team]. Once he's back in full training it can be very quick. He has a good basis, which is what he's working on now."