The franchise was the only one to receive a five-star rating in the Canstar Blue survey, which spoke to small business owners who had used an agent or property manager.
Century 21 placed ahead of First National, LJ Hooker, Raine & Horne, Harcourts and Ray White.
Chairman Charles Tarbey said it was pleasing to receive unsolicited recognition from an independent ratings agency.
“Century 21 has invested significant resources across its network to ensure that clients have a positive experience with the brand and its franchises,” he said.
“To this end, we have coupled personal service and localised real estate knowledge with innovative systems and software to help our agents deliver a superior real estate experience.”