Shop Good (www.shopgood.org) stated it would give the DEC the 15 per cent commission charged on purchases made from retailers such as Homebase, Dixons and Boots through its web site.
The site, which included a prominent DEC banner, claimed that through "guilt free shopping", consumers could help the charity raise £1 million within a year.
However, the DEC, the umbrella body representing 13 aid organisations that work together during global disasters, knew nothing about the initiative.
Neither did Homebase or Boots, both of which denied being approached by the portal's owner, Kevin Shea.
Acting on a tip-off from Third Sector, chief executive Brendan Gormley contacted Shop Good and told the company to remove all references to the DEC. The banner was replaced the next day by an advert promoting celebrity charity auctions.
Shea told Third Sector he was under the impression that the DEC had agreed to the tie-in but admitted that he was not sure consent had been granted by the appropriate person.
He added that all profits would be sent to the Southern Africa Appeal run by the DEC.
Charities that discover commercial companies using their name without permission can take court action to obtain an injunction under section 52 of the Charities Act 1992.
A spokesperson at the Charity Commission said: "A charity's name is a valuable asset and we would expect the trustees to take steps to safeguard it. Charities are by no means powerless if they find that a commercial company has used their name without permission."