OBJECTIVES: Arthritis is associated with poor quality of life (QOL) among older adults; and QOL is even worse among those with arthritis and multimorbidity (MM). Illness intrusiveness and perceived control have been identified in studies of single illnesses as modifiable mechanisms for QOL, but are understudied in older adults with arthritis and MM. We investigated the role of these potential mechanisms with QOL among older adults with arthritis and MM. METHODS: Secondary analysis of a sample of older adults aged ≥ 62 years with arthritis and MM (N = 228) using PROCESS macro for SPSS. RESULTS: Participants were on average 72 years with 4 chronic illnesses, and high levels of pain intensity and illness intrusiveness. Perceived control was a significant mediator (but not moderator) in the relationship between illness intrusiveness and QOL, even after adjustment for pain intensity [β = -0.16, 95% CI (-0.13, -0.06)]. CONCLUSIONS: Lower levels of illness intrusiveness were associated with improved QOL through greater perceived control. Longitudinal studies are needed to further assess these mechanisms in older adults with arthritis and MM to adapt existing interventions. CLINICAL IMPLICATIONS: Perceived control may be a target for future behavioral interventions to improve QOL in this population.