Sustainability is an essential part of the work of publishers. Here, the view of an open access publisher, MDPI, is presented with regards to sustainability within publishing. MDPI’s understanding of sustainability is given and some of the concrete actions it leads to. These include supporting umbrella initiatives, exploring alternative business and editorial models, elements of open science, and ensuring the long-term sustainability of published content. Our aim is to demonstrate actions that could be taken by other publishers and to invite dialog with the broader research community for how a large open access publisher can contribute to a sustainable knowledge ecosystem.