The 2013 Africa Cup of Nations Cup winner returned to London last week after he went to Nigeria to be feted by the President.
Obi’s compatriot, Victor Moses returned before the midfielder and played his first game against Brentford last Sunday in Chelsea’s 4-0 win in the fourth round of the FA Cup.
Chelsea manager, Rafael Benitez explained on the club’s official site that Mikel return will allow Frank Lampard to be rested.
“It's important to be fit and train properly, and Frank will not be in the squad tomorrow as we have to manage the group and think about all the other games,” Benitez told chelseafc.com.
Before the match against Brentford last Sunday, Benitez had expressed happiness to have both his Nigerians back and in good shape.
"I think they will come back with more confidence, more belief and it has to be good for the team," Benitez said.
"It's important to have happy and confident players around, so it's good for the team that they won and they've brought that confidence and belief back with them.
"Both of them progressed as individuals through the tournament.
"Obi has more experience and you could expect good performances from him, but Victor was coming through and I could see he has been growing and improving.
"I am really pleased for both of them, and to be so influential is a great achievement for Victor."
Mikel has played 15 league matches, five times in the FA Cup and five matches in Europe.