Background As high as half of older adults in nursing homes (NHs) live with depression globally. This is associated with suicide, poor quality of life, increased use of acute care services, among other negative impacts. While depression can be attributable to many causes, cultures in NHs are viewed as contributing to the cause of depression. Objective This review aimed to understand how, why and in what contexts person-centred cultures, the expected cultures of care in NHs, contribute or not to the amelioration of depression among older adults using realist review. Methods Realist review is a theory-driven review that explains whether or not an intervention works, how, why and in what contexts in the form of theories. The theories are in the form of contexts (factors that enable or constrain the intervention), mechanism (the resource provided by the intervention and the reasoning/ response of stakeholders), and outcome (expected or unexpected change)- CMOs. This review  was informed by four initial programme theories (IPTs). Evidence was gathered in the form of CMOs from eight data bases to refine the IPTs in collaboration with expert and local reference panels. Results Forty CMOs derived from thirty rich and relevant papers informed the refinement/development of 6 programme theories (PTs), explanations of how person-centred cultures can contribute to the amelioration of depression. The PTs explain the importance of leadership and staff skills development, care processes that promote autonomy, environmental (physical and social) and organisational enablers and social connections in ameliorating depression among older adults in NHs. Conclusion By explaining how specific resources, reasoning and responses of staff and older adults interact with specific contexts in NHs to contribute to the amelioration of depression among older adults, this review offers practical insight to stakeholders in NHs sector on how to bridge the gap between practice, policy, and organisation.