Offshore platforms, subsea pipelines, wells, and related fixed structures supporting the oil and gas (O&G) industry are prevalent in oceans across the globe, with many approaching the end of their operational life and requiring decommissioning. While structures can possess high ecological diversity and productivity, information on how they interact with broader ecological processes remains unclear. Here we present an overview of recent ecological research in Australia that examines the influence of oil and gas infrastructure on marine communities present and on seascape ecological connectivity. Key findings include 1) historical ROV imagery has limited application for science, 2) infrastructure communities are diverse, abundant, and inherently variable, 3) new installations can and should benefit fishery target species, 4) infrastructure facilitates vertical and horizontal seascape connectivity for larvae, mobile adult invertebrates, fish, and megafauna. We discuss the potential impacts of different decommissioning approaches on marine communities present and seascape connectivity and identify critical knowledge gaps, that if addressed, may further inform decision making for the life cycle of infrastructure, with relevance for other industries (e.g. renewables).