The 24-year old attacker has not played for the Gunners since sustaining an abdominal injury in mid-September but will go into the matchday squad for Saturday's visit of former club Southampton.
"He is one of the players who goes behind (the defence) without the ball," Wenger told Arsenal Player.
"Strikers who get behind the defenders is a very important quality and Theo has that quality.
"Of course you miss a player like Theo Walcott. Theo had a good start to the season, he scored goals, he provided chances and had assists. He can always give you a different option in the game and that is of course vital.
"You always want to have a perfect balance (in attack). If you look at our results our balance was not too bad.
"But Theo has different qualities to other players and I am very pleased that he's back."
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