A statement from the ACMA said the fine was levied after an investigation into complaints from consumers about the company's marketing practices.
Service Seeking caters to those looking to hire local trade professionals.
"Businesses that use SMS marketing must make sure the recipient has given permission to be contacted," ACMA chair Nerida O'Loughlin said.
"This is also a timely reminder that all SMS marketing must identify who sent the message and enable the recipient to opt out from future messages."
The statement said that consent-based marketing was one of three areas being targeted for compliance by the ACMA as far as unsolicited communications were concerned.
It said: "The penalties for breaching Australia’s spam rules can be serious for businesses. Where businesses are found to be breaking the rules, the ACMA can seek a civil penalty and/or injunction from the Federal Court; give an infringement notice; accept a court enforceable undertaking; or issue a formal warning."
Complaints about SMSs that could be breaching the rules can be made here.