Referee Mark Clattenburg will not face disciplinary action over a complaint of alleged inappropriate language.
A statement from the Football Association read: "The FA has concluded its investigation into alleged misconduct by Mark Clattenburg during the match between Chelsea FC and Manchester United FC on 28 October.
"No disciplinary action will follow against Mr Clattenburg."
Chelsea had accused Clattenburg of using inappropriate language towards midfielder John Obi Mikel in their 3-2 home defeat by Manchester United on 28 October.
It was also announced on Thursday that Mikel had been charged by the FA for an "alleged use of threatening and/or abusive and/or insulting words and/or behaviour in or around the match officials' changing room."