To investigate the impact of marriage on multiple myeloma (MM) survival, and the role of factors such as age, sex, and income in this relationship. The Surveillance, Epidemiology, and End Results (SEER) database was searched for eligible MM patients between 2007 and 2016. We compared overall survival (OS) and cancer-specific survival (CSS) differences by the Kaplan-Meier method and log-rank tests. The hazard ratios (HRs) with 95% confidence intervals (CIs) for OS and CSS were estimated by Cox regression models. A 1:1 propensity score matching (PSM) analysis was used to minimize the covariates differences between married and unmarried group. This study identified 48,952 eligible patients diagnosed with MM, comprising 29,607 married patients, 5,147 divorced/separated patients, 6,851 single patients, and 7,347 widowed patients. Married MM patients were found to be an independent protective prognostic factor for OS and CSS (all P < 0.001). The survival advantage of marriage still remained in 1:1 matched-pair analysis. The stratified analysis further revealed that the OS and CSS was poorer in unmarried than married MM patients across different age of diagnosis, sex, income, race, and period of diagnosis subgroups (all P < 0.05). The beneficial effect of marriage on the survival of MM was particularly prominent in younger (<65 years) patients, males, higher income patients, non-Hispanic whites, and more recent years. Married patients with MM tend to have better OS and CSS likely due to their higher income, education level, insurance and receipt of chemotherapy.