The British company's website advertises anti-stab vests for $69.95 and says they can be decorated with customised slogans or team colours.
As part of its pitch, it quotes crime statistics on South Africa, which has one of the world's highest rates of violent offences.
Local World Cup organising committee spokesman Rich Mkhondo condemned the vests as an "abominable money making ploy using fear tactics."
Mkhondo said in a statement: "Sport fans visiting South Africa have never needed stab vests. They will not and will never need them during the World Cup...The marketing of stab vests is a joke."
The phone number on the website does not work and comment was not immediately available from the company, which is registered with an address in Merton, southwest London.
South African and World Cup officials are sensitive about suggestions that violent crime will mar the football spectacular, the world's most watched sports event, which is expected to attract 450,000 foreign fans.
South Africa has one of the world's highest rates of violent crime, with around 50 murders a day, but police say fans will be well protected by more than 40,000 police.
Protektorvest is marketing stab proof vests as the best "personal protection clothing for the World Cup."
The website adds: "Our PROTEKTORVEST offers effective protection from potential attacks from blades, knives, bottles and broken glass and turns your stab vest into a special and exclusive fan article."
It offers to deliver the vests directly to a fan's hotel in Johannesburg or Pretoria next June.
Police were on Monday hunting two men who made threats on a local television programme to kill and rob fans at the World Cup.
