FIFA proposed toughening the sanctions after Real Madrid forward Vinicius Junior said he was racially abused by Benfica's Gianluca Prestianni, who covered his mouth while talking to the Brazilian during a Champions League match in February.
Vinicius was visibly upset following the comment and immediately informed the referee, with play halted for 10 minutes in line with UEFA regulations.
Any similar incident at this summer's World Cup will now result in a red card after the rules were strengthened by unanimous agreement at a meeting of the game's lawmakers, the International Football Association Board, in Vancouver, British Columbia, on Tuesday.
An IFAB statement outlining the law change read: "At the discretion of the competition organizer, any player covering their mouth in a confrontational situation with an opponent may be sanctioned with a red card."
Players who walk off the pitch in protest at refereeing decisions -- and officials who incite players to do so -- will also face instant dismissal at this summer's finals, again following a recommendation from FIFA to the IFAB, ESPN reported.
A team that causes a match to be abandoned will, in principle, forfeit the match.