<p>Greening of grey infrastructure (GGI), a type of nature-based solution which strives to enhance marine life along increasingly artificial urban shorelines, is widely recognised for providing environmental benefits. Yet research into the benefits for society remains scarce. Understanding social perceptions of GGI is crucial, as public buy-in and expert support is essential for successful implementation. Using the Living Seawalls in Plymouth, United Kingdom, as a case study, we conducted a social perception study using questionnaires at expert workshops held prior to the Living Seawalls’ installation, and at public events following the installation. We gathered data from experts from relevant sectors, such as natural and built environment professionals and government employees, in addition to members of the public, gauging support for GGI, willingness to pay, and potential drivers of differing opinions. Both groups expressed positive perceptions and high levels of support. Almost all respondents expressed support for greening existing seawalls (99%) and a willingness to pay for GGI through increased council tax (96%), indicating large potential sums at the population level. This study contributes to the growing body of evidence indicating strong support for GGI, adding a novel perspective by including both expert and public views within a UK context. Findings suggest that GGI could be effectively scaled through appropriate funding mechanisms. By highlighting the role of public and expert support, this study demonstrates how socially informed nature-based solutions can contribute to the design of more ecologically resilient urban systems, a practical pathway towards achieving the goal of sustainable coastal cities.</p>