The 17-year-old joined the club on loan at the beginning of September, with Zola calling his performance against Bristol City "top class".
"I thought for 25 minutes, or 30 minutes, he was quite outstanding. His performance was really top class and he played well when he also went to the back," Zola told the Watford Observer.
"He is a player that if he maintains the right attitude and keeps working and focusing on learning then he could really become an important player. He can go as high as he wants to."
Chalobah has been tipped as a future star for Chelsea.