"Mikel will soon sign a new five-year deal with Chelsea. He will sign a new five-year contract with obviously an improved salary," said the player's agent John Ola Shittu.
"We are just about finalising the details of the deal and it can be announced anytime soon by the club.
"He has a year left on his contract and Chelsea has decided to add four more years to it."
However, Shittu refused to disclose the financial aspects of the new deal for his player, who is reportedly on about 80,000 pounds a week.
In 2006, Mikel opted for Chelsea ahead of Manchester United  in a long-drawn transfer saga.
Shittu said the player is now been rewarded for his consistency.
"He is one of the most consistent performers and the club management agree with us that he deserves a new and improved contract," he said in an interview published by daily sports paper Complete Sports.
The Nigeria international has won several major trophies with 'The Blues' including a historic UEFA Champions League last season as well as a league and cup double in 2010.