Background: With improving survival for patients with multiple myeloma (MM), supportive care that is focused on optimizing quality of life and minimizing treatment-related toxicities is increasingly important. The extent to which patients with MM are receiving recommended supportive care is unknown. Methods: This study used the Surveillance, Epidemiology, and End Results–Medicare database to identify older adults (age ≥66 years) diagnosed with MM in 2008-2013 who had received active treatment and survived 1 year or longer after their diagnosis. Outcomes of interest included guideline-recommended supportive care, which was defined as 1) bone-modifying drugs (BMDs) within the 12 months after the diagnosis, 2) influenza vaccination in the first season after the diagnosis, and 3) concomitant use of prophylactic antivirals with proteasome inhibitors. Multivariable logistic regression models were used to evaluate associations between patient/facility-level characteristics and supportive care use. Results: Among 1996 patients receiving MM-directed therapy, 64%, 52%, and 49% received BMDs, an influenza vaccination, and antiviral prophylaxis, respectively. Non-Hispanic black patients (odds ratio [OR] vs white patients, 0.63; 95% confidence interval [CI], 0.46-0.88) and patients with baseline renal impairment (OR, 0.43; 95% CI, 0.34-0.54) had lower odds of BMDs. Non-Hispanic blacks (OR, 0.52; 95% CI, 0.37-0.73) and those with dual Medicaid enrollment (OR, 0.76; 95% CI, 0.58-0.99) had lower odds of influenza vaccination. Treatment in a community-based setting was associated with reduced odds of antiviral prophylaxis (OR, 0.58; 95% CI, 0.46-0.72). Conclusions: Substantial underutilization of guideline-recommended supportive care was observed among older adults with MM in the United States, and this was associated with both patient and facility characteristics. Targeted interventions are needed to improve supportive care for patients with MM.