Ramsey has been sidelined since the home defeat to Watford at the end of January due to a calf injury, while Koscielny was forced to sit out the FA Cup victory over Sutton United last month.
However, both players are expected to be available for selection when the Gunners travel to Anfield this weekend, although Wenger did also confirm that Mohamed Elneny faces a spell on the sidelines.
"We have Aaron Ramsey back in the squad. He's back in full training. Laurent Koscielny, who we lost at Bayern Munich, is back in full training as well," he told reporters.
"Elneny has an ankle problem that should be sorted out in three weeks. He got injured at Sutton and will not be available for Saturday's game."
Arsenal currently sit fourth in the Premier League table, one point clear of Liverpool with a game in hand.