The former West Ham United and Everton man says the recent form of the 25-year old Vatreni forward gives the Glasgow giants a great chance of reeling in Old Firm rivals Celtic and taking their third title on the trot.
Nikica has already shown his quality. "He is powerful, has pace, skill and can score goals. He is the complete striker," Bilic said.
"He has had a hard time with injuries but he still has a fantastic goal record and has become a big player very quickly.
"However, there is much more to come from him. He is young and still learning and improving.
"We have not seen the best yet. He will get better over the next few years.
"This is his first season in a new league and he deserves a lot of praise for the way he has handled the move. He will be very important in the final few games."
Bilic added that Jelavic can become a force in the Croatian national team and in turn will improve his already top-notch performances for Rangers.
"When he has worked with me for the national team, I have been very impressed," he added.
"We have a lot of quality strikers but Nikica is a vital member of the squad. If he continues to progress the way he has been, Rangers and Croatia will benefit."