Mikel's father Michael was seized on Friday but the player insisted on playing in his club's Premier League opener at the Britannia Stadium.
In a statement, Mikel's representatives Sport Entertainment and Media Group said: "SEM confirms that client John Obi Mikel's father was abducted in Nigeria on Friday, August 10 (sic.). Thus far no ransom demand has been received. Mikel was informed by his manager prior to the Stoke v Chelsea match and decided to play so as not to let down his team and family."
Michael Obi, who runs a transport company, has not been seen or heard from since he failed to return home from work in Jos, the capital of Plateau State in central Nigeria.
Speaking on Sky Sports News, Mikel said he and his family are yet to hear anything regarding his father's whereabouts or who might have taken him, and he made a direct appeal for his father's release.
He said: "Please just let him go. He's just an old man, he hasn't done any harm to anyone as far as I know and I don't know why he has been taken."
Mikel's agent John Ola Shittu praised his client for the character he showed in turning out against Stoke.
"He is totally devastated. We were not sure whether to tell him before the game," he told KickOffNigeria.com. "But after speaking to the manager (Andre Villas-Boas) and Mike Emenalo (Chelsea's sporting director) we agreed that he had a right to be informed of such a serious incident.
"He was under a lot of stress but he showed a lot of character and mental strength to play against Stoke."
Shittu told the BBC: "It's been tough for the young man. The family in Jos reported him missing at the police station as expected but we're taking all necessary measures to find him. We've told him to be brave and to stay calm."
Mikel is not the first Premier League player to have a family member abducted in Nigeria.