Kante joined Antonio Conte's side from Leicester last summer and has made an immediate impact at Stamford Bridge.
The Frenchman has thrived in a 3-4-3 formation, with his energetic displays helping Chelsea climb to the top of the Premier League table.
Kante is vying to secure a second successive winners' medal and is also in the running for the PFA Player of the Year award.
The likes of Eden Hazard often receive the limelight at Chelsea but Costa is adamant the work Kante does in the engine room is invaluable.
"Kante is the team’s heart," Costa told Chelsea's official website.
"He is a player who gives us a lot of things: he scores for us and on the field he offers a huge support, not so much for me personally because of my position at the front.
"But he is always there for the defenders and midfielders. He is an impressive player.
"All you need to think is he left Leicester and Leicester has not had such a good season compared to the previous one, so you really notice a lot when a player like him goes," he added.
Chelsea travel to Bournemouth this evening aiming to strengthen their position at the top of the table.
Costa has not scored in three top-flight fixtures but remains determined to play his part during the run-in.
"We are playing to win a championship. During the previous season I was out a lot of the time, either because of a suspension or an injury.
"So this year I really want to play the remaining matches and enjoy myself here in Chelsea," Costa insisted.