Mikel joined Chelsea in 2006 when he was still a teenager and went on to form a solid midfield partnership with Essien.
Both players helped the English side to win multiple Premier League and FA Cup titles, as well as the UEFA Champions League.
Speaking about his early days at Chelsea, the Nigerian said he was nearly overawed by the star names in the dressing room.
He noted that it was Essien who helped him settle at the club by aiding him to make basic decisions like when to pass, dribble or control the ball.
"Suddenly, I was sharing a dressing room with all these players I had watched on television back in Africa," Mikel told the Athletic.
"I was sitting next to Lassana Diarra. I'd be there thinking, 'Oh my God, it's Didier Drogba. It's Frank Lampard. It's John Terry'."
He added: "Michael Essien (who joined from Lyon in the summer of 2005) really helped me. Michael always told me I was a good player and just reminded me to bring the ball down, control and pass. If you need to dribble, dribble. If you don't need to, just pass. You are strong. You are fast, too.
“If you can, just push the ball past and run, run, run because they cannot catch you. He was the guy who really helped me and made me have a lot of confidence."
Mikel, 34, currently plays for Kuwaiti topflight side Kuwait SC.