(1) Background: Dietary behaviour transformation is imperative for the attainment of more sustainable food systems, including an increased intake of plant-based foods and lower consumption of red meat and highly processed foods. The influence of news media coverage on public opinion regarding dietary behaviours is significant. Therefore, this study aimed to explore how sustainable/plant-based diets have been portrayed in Australian news media. (2) Methods: The Factiva global news database was used to search news articles published in Australia between 2018 and 2020. Relevant news articles were selected if they included keywords relating to sustainable diets, plant-based diets, and meat alternatives. We used a coding protocol to extract key information, such as date of publication, article topic, and any health, environmental and economic impacts. Then, we performed a framing and thematic analysis of the data. (3) Results: From 357 included articles, more than half of the articles encouraged increasing the intake of plant-based foods (53.5%) and reducing animal-derived food intake (55.2%). Several reasons for such shift from animal protein centric Australian diets were identified throughout the articles such as health benefits (15.4%), environmental impacts (11.2%), animal welfare (4.8%), seasonality and local food intake (5.3%), avoiding overconsumption (4.5%) and food wastage (4.5%). (4) Conclusions: The predominant frame in Australian news coverage about sustainable diets has been about consumption, more plant- and less animal-based products, with little nuance about the complex interplay of diet quality and environment in influencing food choices. Australian news media should broaden its coverage of sustainable diets to include health, environmental, and economic factors to improve public understanding and facilitate informed and sustainable food choices. Further research is needed to enhance comprehension of how the audience perceives media coverage on this topic, which will provide a more thorough understanding.