The rise in tourism arrivals and the need for the achievement of sustainability goals have also caused an ever-growing attention towards sustainable tourism. Recently, online platforms and tour operators have become one of the most common means of booking in tourism. The objective of this chapter is to identify to what extent and how the concept of sustainability can be integrated within these websites and whether this has already been done. Additionally, a set of life-cycled-based indicators is aimed to be identified or proposed for the selection of sustainable accommodation within these websites. Tourists would therefore be assisted in choosing the most sustainable option of accommodation, in the same way as they can already do today when choosing the most convenient fare or the most suitable location and features. In order to identify the integration of sustainability in these cases, a literature review was performed. Furthermore, the inclusion of such schemes or possible indicators was analysed through the examination of the most visited online booking websites. Thus, the ways the various platforms have introduced for the communication of the sustainability of their suppliers’ accommodation services was identified and analysed. Moreover, the various modes or filters implemented for the selection of the accommodation on behalf of the users was examined. The online booking platforms can be important for the promotion of sustainable tourism; however, the results of the literature review show that this issue has not been tackled with so far in depth.