Understanding habitat requirements for a threatened species is important for recovery planning and management of threatening processes. This study examines utilisation of wetland habitat by the threatened wallum sedge frog (Litoria olongburensis), which breeds in acidic waters of coastal sandy lowlands in subtropical eastern Australia. Habitat utilisation was determined by comparing perch substrate observations with perch substrate availability in wetlands occupied by the species throughout its mainland distribution range. A high proportion (75.3%) of adult wallum sedge frogs perched on upright sedges, comprising Baumea, Schoenus and Chorizandra species, which was much higher than expected on the basis of availability (P < 0.001). Baloskion pallens, a thin sedge-like herbaceous plant, was utilised by 12.1% of the frogs, which was lower than expected on the basis of availability (P = 0.020). Other herbaceous species and shrubs were also utilised significantly less than expected. The identification of preferred perch species is critical for impact assessment and mitigation activities, including design, construction, restoration and maintenance of wetlands suitable for the survival and reproduction of the wallum sedge frog.