The Consumers' Association is the first charity to become a "designated enforcer" under new legislation.
The new powers, granted under Part 8 of the Enterprise Act 2002, will give the association real teeth for the first time, putting it on a similar footing to the Civil Aviation Authority and the Financial Services Authority, also designated enforcers.
It will be able to act where there is evidence of consumer detriment - such as rogue traders exploiting consumers - and where the Consumers' Association is considered the most appropriate enforcer.
The charity can also seek an enforcement order from the courts. Failure to comply with orders can amount to contempt of court, leading to fines or imprisonment. Cross-border enforcement is also available.
Nick Stace, director of communications at the association, said: "This sends a clear message to businesses indulging in dishonest practices to mend their ways. We will have no hesitation in applying these powers if companies step out of line."