The Australian offshore oil and gas industry is facing a significant decommissioning portfolio over the next few decades. In response to this, in 2019, eight Australian oil and gas operators and the National Energy Resources Australia (NERA) established the National Decommissioning Research Initiative (NDRI) with the aim to fill key knowledge gaps on the potential environmental impacts, risks and benefits of different decommissioning options in Australia’s offshore environment. In Phase 1, seven research projects were undertaken covering the interaction that occurs between the environment and oil and gas infrastructure in Australia’s oceans. These projects focused on habitat, connectivity, invasive marine species, degradation of metals and non-metals and potential contaminants of concern such as mercury and naturally occurring radioactive materials. Two other projects were undertaken to gain insights into regulators, stakeholders, marine users and scientist views on offshore decommissioning risks and opportunities. This paper describes the drivers for NDRI, the outcomes of the Phase 1 projects and the future projects to be undertaken to support the environmental assessment of different decommissioning options.