The board's disciplinary officers have secured the convictions against a Worcester business called Rubicon and a private West London individual called Robert Harwood, who was working under the banner 'architectyourhome'.
Rubicon was fined £1,500 and ordered to pay £1,000 while Harwood received only a conditional discharge, but had to pay £1,488.
Both were found to be actively using the title of architect to trade while not being registered with the board.
The ARB was especially pleased with the Rubicon conviction. 'This was a blatant misuse of title,' a spokesman said.
'They wrongly advertised themselves as architects, using the RIBA logo on their signage. This was a serious breach of the Architects Act, and misled consumers into believing they were dealing with properly trained and fully qualified architects.
'ARB regard this behaviour as wholly unacceptable, and will continue to come down hard on firms or individuals who abuse the public trust in this way,' the spokesman added.