Older adults frequently experience depression alongside physical multimorbidity, with mutual reinforcement through biological, behavioural and social mechanisms. Traditional models of care often address these conditions in isolation, resulting in fragmented services poorly suited to the complex realities of ageing. Social prescribing has emerged in the UK as a potential solution, offering structured referrals from healthcare to community-based resources. While its theoretical promise aligns well with the needs of older adults, the evidence base remains limited, and current implementation strategies often fail to match individuals to interventions effectively. This narrative review explores how social prescribing might evolve to bridge the gap between mental health and multimorbidity in later life. Using depression and metabolic syndrome as a case example, we examine shared inflammatory mechanisms, barriers to behavioural change and the risks of individualising structural disadvantage. We propose a future framework in which social prescribing is supported by complexity-sensitive evaluation tools, including patient-reported outcome measures, biomarker-informed stratification and artificial intelligence-driven narrative assessment. We also highlight the critical role of integrated care systems in developing the community infrastructure necessary to sustain these interventions equitably. By reframing social prescribing as part of a broader public health strategy rooted in integration and prevention, we argue it can move beyond symbolic appeal to become a meaningful component of multimorbidity care in older adults.