Offshore windfarms (OWFs) are regarded as a critical pathway for reducing greenhouse gas emissions but may have significant impacts on cetaceans. Uncertainties on the magnitude of these impacts in novel regions for the industry have the potential to create substantial delays in approvals. Decades of research and monitoring in Europe shed light on probable environmental impacts of OWFs. However, at-risk species are very different to Australia and hence not all mitigations and monitoring tools are directly transferable. In Australia, at least 5 of the 6 areas prioritised for OWF development (Declared Areas) overlap with known migratory pathways and/or important habitat for cetaceans. Yet effective monitoring faces the challenge of obtaining adequate statistical power to detect change in populations that typically range dynamically across scales far larger than the Declared Areas. The most robust approach is to combine systematic aerial and vessel surveys with continual passive acoustic monitoring. However, a baseline understanding of annual variation and of the occurrence of rare species is likely to require supplementary datasets such as citizen science and research. Approaches to integrate relevant datasets to inform project planning and to avoid impacts will be discussed.