Background Public support is important for the adoption, implementation, and sustainability of effective climate action. Evidence suggests that policy instrument characteristics, individual characteristics, and the way in which climate messages are framed can influence public support. Evidence on the effectiveness of different climate message framing, however, is largely limited to high-income countries, with limited research conducted in Sub-Saharan Africa, where the impacts of climate change are particularly severe. This study aims to assess knowledge and perceptions of climate change and health among urban residents in Nairobi and to examine how different message framings influence public support for climate policies. Methods A cross-sectional household survey will be conducted among adults (≥18 years) in Nairobi, Kenya. A sample of approximately 903 participants will be recruited through face-to-face household interviews. The survey will begin with a conjoint experiment consisting of eight paired-choice tasks comparing policy messages that vary across four attributes: climate framing, benefits, scale, and funding source. The survey will then collect information on knowledge of climate change and health, perceptions of climate-related health risks, experience of climate-related weather events, and socio-demographic characteristics. Descriptive statistics and multivariable regression analyses will be conducted to examine factors associated with climate-health knowledge and perceptions. Conjoint data will be analysed using marginal means and Average Marginal Component Effects to estimate the influence of message framing on stated support for climate-related policies. Ethics and Dissemination Ethical approval has been obtained from the Observational/Interventions Research Ethics Committee, London School of Hygiene & Tropical Medicine (LSHTM) (Ref: 33680). Local ethics has been obtained from the Kenyatta National Hospital-University of Nairobi Ethics and Research Committee (KNH-UoN ERC, REF: PKU/33392/E40475). The findings of the study will be disseminated through peer-reviewed publications, presentations to the scientific community and interest-holders, and local engagement activities.