People living with dementia are often presumed to have no agency or capacity to act in the social world. They are often excluded from participating in research while research methodologies may not capture their embodied engagement with people and places. Yet, like everyone, people with dementia can express their agency in nuanced ways, for example, through emotions or embodied expression. In the conceptual framework discussed here, nuanced agency is conceived as consisting of non-deliberative elements (embodied, emotional, habituated, reflexive and intersubjective) and deliberative elements (choices or decisions and facilitative). Although people with dementia have been found to benefit from gardens with their sensory appeal, how they experience gardens is not well understood. This critical interpretive synthesis aims to explore how people with dementia experience nuanced forms of agency and citizenship in gardens. A conceptual framework of agency was developed to address the aim and support the analysis. Analysis of the 15 included studies highlighted the value of the conceptual framework in identifying a wider and more granular array of nuanced agency expressed in embodied form and through dialogue. This included expressions of intersubjective and facilitative agency that informed opportunities for people with dementia to experience relational citizenship socially in communal garden settings. These findings suggest an opportunity for researchers to explore the embodied agency of people living with dementia more comprehensively by applying theoretical concepts of agency. Further testing of the framework’s utility for guiding collection and analysis of primary data involving people with dementia in garden settings is recommended.