The Blues claimed a 2-0 victory at Anfield to revive their title hopes and Redknapp was impressed by Mikel's strong defensive display.
"He rarely plays under Jose Mourinho, but John Obi Mikel has been involved in some crucial matches for Chelsea," he wrote in his column for the Daily Mail.
"He was vital in the 2012 Champions League final, he performed so well against Atletico Madrid last week and he was at it again at Anfield.
"It was not pleasing on the eye, but Chelsea's performance was effective and Mikel was key to that. He dropped into the back line to help deal with crosses and he and Nemanja Matic never left any space between the midfield and the back line."
Chelsea are currently second in the Premier League table and sit two points behind league leaders Liverpool.