The adoption of sustainability practices in city hotels is increasingly prevalent, driven by the imperative to reduce environmental impact, comply with regulations, and meet the growing demand for sustainable offerings. These practices serve to differentiate city hotels from traditional brands and bolster brand identity. However, the extent to which sustainability initiatives contribute to a hotel's objectives and are perceived by guests remains debated. This study, conducted in Nairobi County, assessed the impact of sustainability practices on brand identity and guest travel preferences. It explored the mediating role of travel preferences in the relationship between sustainability practices and brand identity, as well as the moderating influence of length of stay. Drawing on the Triple Bottom Line (TBL), Environmental Attitude Behaviour (EAB), and Brand Identity Prism (BIP) frameworks, survey data from 205 guests across 36 classified hotels in Nairobi were analysed using structural equation models. The results confirmed a positive and significant relationship between sustainability practices and brand identity, as well as their impact on guest travel preferences. While mediation effects were not observed, the study revealed that both short and long stays significantly moderated the relationship between sustainability practices and brand identity. This research contributes empirical evidence on the interplay between sustainability practices, guest preferences, and brand identity across different lengths of stay. It suggests that hoteliers can leverage environmental and social sustainability initiatives to cultivate a brand identity aligned with guests' environmental and hedonic inclinations, thus gaining a competitive edge in the city hotel market