Mikel was informed on Saturday morning that his father had not returned home after work on Friday in the Nigerian city of Jos and had not been contactable by telephone, and he has not been seen since.
Mikel's manager, John Shittu, told Kick Off Nigeria: "At the moment we have not heard from Mikel's father, or anyone else, so we don't know what it is. At this point, we only consider him missing."
Mikel played the full 90 minutes for Chelsea in their 0-0 draw at Stoke on Sunday but Shittu added: "He is totally devastated. We were not sure whether to tell him before the game, but after speaking to the manager, and [Chelsea technical director] Mike Emenalo, 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 added in a statement to 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's representatives, Sport Entertainment and Media Group, have said it is an abduction.
"SEM confirms that client John Obi Mikel's father was abducted in Nigeria on Friday, August 10," a statement read. "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."