The midfielder was enjoying a rich vein of form this season, before suffering a thigh injury in the Boxing Day victory over West Ham.
Wenger admitted Ramsey's return is a welcome boost for his side, which has seen its title challenge slip away in recent weeks and now faces real competition from the Toffees for the fourth Champions League spot.
"He drives the team forward and he is a box-to-box player. It's good to have him back," Wenger told reporters.
Ramsey bagged eight goals in 18 Premier League appearances before succumbing to injury and will hope to pick up where he left off to help the out-of-form Gunners, who have won just three of their last 10 top-flight outings.
Fullback Nacho Monreal is also available for Sunday's crucial clash, but Kieran Gibbs is struggling with an ankle problem, while Serge Gnabry has a knee injury.