Background and Objectives: Caregiving outcomes have often been reported in terms of care recipients of single disease, rather than multiple health conditions. A systematic review was conducted to outline caregiving health outcomes and its association with care recipient multimorbidity for informal caregivers of older adults.; Research Design and Methods: A search strategy was applied in six databases and grey literature. Inclusion criteria were primary observational studies on informal caregiving for care recipients aged 60 years and above, in the English language. Informal caregivers were those not formally hired and multimorbidity referred to presence of at least two health conditions. From a total of 2,101 titles, 230 abstracts were screened, and 19 articles were included. Quality assessment was conducted with application of the Newcastle-Ottawa-Scale.; Results: Health-related and caregiving-related outcomes have been assessed for informal caregivers of older adults with multimorbidity. Caregiver subjective burden was most commonly evaluated and often reported to be low to moderate. In association with care recipient multimorbidity, caregiver burden, quality of life, and perceived difficulty in assisting the older adults were examined in 14 of the studies with mixed results. Studies were heterogeneous, with nonuniform definitions of informal caregivers and multimorbidity as well as measurement tools.; Discussion and Implications: This narrative review found that caring for older adults with multimorbidity impacts caregivers, although overall evidence is not conclusive. Despite caregiving-related outcomes being most commonly assessed among the caregivers, particularly subjective burden, findings suggest that it is worthwhile to examine other outcomes to enrich the evidence base.