The International Football Association Board (IFAB), football's rule-making body, said the decision followed a growing trend in Brazil.
In the move known as the Paradinha (Little Stop), players stop as they are about to take the penalty, send the goalkeeper the wrong way with a dummy and cheekily chip the ball into the empty part of the goal.
"We saw some video examples, which make it clear it's very unsporting when the player gets to the end of a run up, feints to kick completely over the ball, the goalkeeper goes in one direction, the player pulls his foot back, and kicks the ball in the other direction," IFAB member Patrick Nelson told reporters.
"It's clearly unsporting."
One IFAB member added that some of the dummies on the video had the room in fits of laughter.
FIFA general secretary Jerome Valcke admitted it would be a race to introduce the new rule in time for the World Cup.
"It's something we have to implement in 23 games," he said.
"We have to make sure the referees, players and coaches understand what it is about and will use videos as an example for the players to see where we are coming from."
Players who feint as they are about to take the kick will be shown a yellow card. However, feinting during the run-up will be allowed.
The new wording of Law 14 now reads: "Feinting in the run-up to take a penalty kick to confuse opponents is permitted, however, feinting to kick the ball once the player has completed his run-up is now considered an infringement of Law 14 and an act of unsporting behaviour for which the player must be cautioned."
The practice also came to prominence with an ugly incident during the African Nations Cup.
Algeria goalkeeper Faouzi Chaouchi, enraged when Egypt's Hosni Abd Rabou feinted before stroking his spot-kick into the net to during their semi-final, chased the referee, grabbed him from behind and head-butted him before being dragged away by team-mates.
Referee Bonaventure Coffi Codjia was suspended for failing to dismiss Chaochi in the incident, although the Algeria goalkeeper was later sent off for a second bookable offence in their 4-0 defeat.
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