David Grant, head of Inspire Designs in east London, was found guilty of breaching Section 20 of the Architects Act, and was ordered to pay £1,500 in fines and costs by Stratford magistrates.
Grant did not attend the 6 September hearing, nor did he submit any mitigation in his defence.
A spokesman from the ARB's regulation department said after the hearing: 'Mr Grant had falsely advertised his firm under an 'Architects' listing in the Estates Gazette.
'This was a blatant attempt to mislead members of the public into believing that his firm was a reputable firm of architects. Not only does this mislead consumers, it also undermines the profession's integrity in the eyes of the public.'
The spokesman added: 'The board remains committed to prosecuting individuals who act in such a manner.'