Millwall have been charged by the Football Association after some fans allegedly chanted racist language during the FA Cup fourth-round win over Everton in January.
Supporters could be heard using a racist term that is derogatory to the Asian community during the game.
In the aftermath of reports, Millwall said they will "ban for life" anyone identified using racist abuse.
The chants followed crowd trouble near to The Den before the game started.
A man was slashed across the face during a mass brawl which the Metropolitan Police believed involved groups of rival fans.
The FA says Millwall have been charged with a breach of rule E20.
"It is alleged the club failed to ensure its spectators conducted themselves in an orderly fashion and refrained from using abusive and/or insulting words, which included a reference to race and/or ethnic origin, during the Emirates FA Cup tie against Everton on 26 January 2019," a statement read.
Murray Wallace scored a 94th-minute winner as the Lions beat the Premier League club 3-2, with Millwall scoring a controversial equaliser when Jake Cooper appeared to handle the ball.