This study examines associations between lifestyle behavioural factors and appraisals of “healthy aging” among older adults experiencing multimorbidity. A Social Determinants and Health Behaviour Model (SDHBM) is used to frame the analyses. Using baseline data from the Canadian Longitudinal Study on Aging (CLSA), we studied 12,272 Canadians 65 years of age or older who reported 2 or more of 27 chronic conditions. Additional analyses were conducted using three multimorbidity clusters: cardiovascular/metabolic, musculoskeletal, and mental health. Using hierarchical logistic regression, it was found that, for multmorbidity and the three illness clusters, healthy aging is consistently associated with not smoking (except for the mental health cluster), an absence of obesity (except for the cardiovascular and metabolic cluster), better sleep, and a better appetite. It is not associated with inactivity. Several socio-demographic, environmental, and illness covariates were also supported. The findings are examined using the SDHBM coupled with a resilience lens in order to elucidate how modifiable health behaviours can act as resources to mitigate multimorbidity adversities. This has implications for healthy aging for persons with multimorbidity, especially during the COVID-19 pandemic.