Thirty-two-year-old Terry was forced to watch the Blues from the sidelines after he suffered a knee injury during a Premier League encounter against Liverpool at Stamford Bridge in November last year.
However, he has since returned to the squad and his fellow defender Ivanovic believes that the skipper will have a positive impact on the team.
"We need every player but especially John. He is a real warrior and leader of the team, especially as he's captain," said the Serbian. "He is a very important player for us and his injury came at a bad time. It has been a very difficult season for him but he's back now and he will help the team in the future.
"It's always better to have him on the pitch, this kind of player who can shout and organise. He can motivate you and every second he supports you.
"He does well not just for himself but his teammates. It is important to have someone like him on the field, we have missed this."
The knee problem has limited Terry to just 12 appearances in all competitions this season.