The global climate crisis is present in national and international discourse, along with other challenges the world is going through, such as the current wars in Ukraine and Gaza or the recovery from the COVID-19 pandemic, with the negative effects highlighted in the United Nations' sustainable development report. This paper aims to analyse and discuss how higher education institutions (HEIs) in Portugal cope with these challenges and contribute to a more sustainable world. The Portuguese case is interesting because, in recent years, they have been pressed to demonstrate their commitment towards sustainability publicly. We will proceed with framing the current role of Portuguese HEIs and their commitment to a sustainable world. This implies taking stock of their engagement with university social responsibility (USR), a concern of HEIs that is transversal to their roles -- research, teaching, and service to society -- but emphasises developing environmental sustainability and engaging students in active citizenship. Our argument is based on the importance that HEIs play in the sustainable development of societies, particularly in terms of environmental sustainability. Through documentary analysis of the strategic plans of HEIs, we explore if sustainability emerges and how it is framed in terms of policies and practices, contributing to a reflective debate on HEIs' potential role in addressing current challenges and committing to a more sustainable world. Therefore, the findings suggest that institutional diversity and territorial inequalities are important elements for understanding how different public HEIs in Portugal conceive and practice sustainability.