The adoption of sustainability practices in city hotels has become a trend driven by the need to mitigate the environmental footprint, comply with regulations, and cater to the increasing demand for sustainable products. Lifestyle hotels adopt sustainability practices to differentiate themselves from traditional hotel brands and enhance brand identity. However, the effectiveness of sustainability practices in contributing to a hotel's sustainability objectives and how guests perceive them remains a topic of debate. This study focused on lifestyle hotels in Nairobi County. The study assessed the influence of sustainability practices on brand identity and guest travel preferences. It analyzed how travel preferences affect brand identity and explored the mediating role of travel preferences in the relationship between sustainability practices and brand identity. Additionally, it examined the moderating impact of guest attributes, such as generational cohort, length of stay, and repeat visit, on the relationship between sustainability practices and brand identity. The study hinged on the Triple Bottom Line (TBL), Environmental Attitude Behavior (EAB), Brand Identity Prism (BIP), and Generational cohort’s theories to define the variables and their relationships. The research adopted a mixed-method approach and explanatory sequential mixed method design to collect data using questionnaires from a random sample of hotel 205 guests in 35 city hotels and a semi-structured interview guide to collect data from 19 managers in lifestyle hotels. The study relied on descriptive statistics to profile the respondents and structural equation modeling to develop measurement models for the study variables and estimated structural models of the relationships between the study variables. The results of the structural models were used to test the research hypothesis. Thematic analysis was used to analyze patterns in experiences and perceptions of the hotel managers on sustainability practices, and brand identity. The study showed that implementing hotel sustainability practices (HSPs) positively affected brand image (β₂ = 0.92, t = 3.11, p < 0.05). It also found that HSPs positively impacted guests' travel preferences (β₁ = 0.87, t = 6.30, p < 0.001), indicating alignment with pro-environmental and hedonic preferences in lifestyle hotels. However, no evidence suggested a relationship between guests’ travel preferences and brand identity (β = -0.03, t = - 0.11, p = 0.91ns), indicating that guests’ experiences at the hotel shaped brand evaluation more than pre-consumption dispositions. Similarly, travel preferences did not mediate the HSP-brand identity relationship (𝐵=−0.03,𝑝=0.96𝑛𝑠). Long and short stays both moderated this relationship, with long stays strengthening the influence of HSP on brand identity. Repeat visits also moderated this influence, with heightened impact on brand identity for repeat visitors. Generational cohort generally did not significantly moderate the HSP-brand identity relationship, but Millennials showed a notably stronger response in the relationship between HSP and brand identity compared to other cohorts. Research findings contribute to the body of knowledge on the theoretical relationship between HSP, travel preference and brand identity in lifestyle hotels, an emerging niche segment. Hoteliers can rely on the results of the study to prioritize environmental and social sustainable practice to positively impact on the hotel’s sustainability brand image, promote loyalty, increase repeat visit and target millennials as a market segment for lifestyle hotels. The study recommends future research to investigate the relationship between pre-consumption guests’ attitudes, encompassing environmental and hedonic predispositions, and post-consumption outcomes, particularly brand identity formation within the emerging lifestyle hotel niche market.