Essien spent the second-half of last season away on-loan at Real Madrid.
"He seems to be back to the real Michael Essien," Cech told the Daily Mail. "He's always been a fantastic player and the only unlucky things were the injuries. He's back and if he stays fit then it will be great to have him.
"It was a great thing for him to happen, to go on loan last year and enjoy a great season with Real Madrid. He was unlucky with back-to-back injuries and he had to work very hard to come back.
"That loan made sure he played more than he could have played and, as you can see, he's happy, he's back, he's fit and he will be very useful for us."