There are many health and nutrition implications of suffering from multimorbidity, which is a huge challenge facing health and social services. This review focuses on malnutrition, one of the nutritional consequences of multimorbidity. Malnutrition can result from the impact of chronic conditions and their management (polypharmacy) on appetite and nutritional intake, leading to an inability to meet nutritional requirements from food. Malnutrition (undernutrition) is prevalent in primary care and costly, the main cause being disease, accentuated by multiple morbidities. Most of the costs arise from the deleterious effects of malnutrition on individual’s function, clinical outcome and recovery leading to a substantially greater burden on treatment and health care resources, costing at least £19.6 billion in England. Routine identification of malnutrition with screening should be part of the management of multimorbidity together with practical, effective ways of treating malnutrition that overcome anorexia where relevant. Nutritional interventions that improve nutritional intake have been shown to significantly reduce mortality in individuals with multi-morbidities. In addition to food-based interventions, a more ‘medicalised’ dietary approach using liquid oral nutritional supplements (ONS) can be effective. ONS typically have little impact on appetite, effectively improve energy, protein and micronutrient intakes and may significantly improve functional measures. Reduced treatment burden can result from effective nutritional intervention with improved clinical outcomes (fewer infections, wounds), reducing health care use and costs. With the right investment in nutrition and dietetic resources, appropriate nutritional management plans can be put in place to optimally support the multimorbid patient benefitting the individual and the wider society.