Aguero has been sidelined since March 12, when he came off at half-time in City's 2-1 UEFA Champions League loss to Barcelona.
But the star striker is set to return in his side's crucial league clash against Liverpool at Anfield on Sunday.
Zabaleta said while his team had enough quality to perform without Aguero, the 25-year-old's return had come at just the right time.
"Sergio is fit. He's been training well with the team for a few days now," he said.
"He wasn't 100 per cent to play against Southampton (on Saturday). That's why the manager decided to leave him out and let him be fully ready for the next game against Liverpool.
"Have we missed him? Yes, of course. You always you want the best players in the team and to be fit for any game at this time of the season."
City are the Premier League's second-highest scoring team, six goals behind Liverpool's 90, thanks to the likes of Aguero, Yaya Toure, Edin Dzeko and Alvaro Negredo.
Zabaleta said he could see the reasons for the comparisons to Carlos Tevez, who returned from a self-imposed exile to help City to the title in 2011-12.
"It's a good time for him to come back. I can see why people say it's similar to Tevez returning - although it's a different situation," he said.
"Like with Carlos, it's great for any team to have the best players back in the team again - particularly at this part of the season. That's the good news for us.
"He's an important player and he's going to score goals. He's fast, he's quick. Sometimes we need a player like Sergio."
