While much research has focused on the direct impact of socioeconomic status on cancer patients, what is not clear is the impact of socioeconomic status on social support and the burden of care for caregivers. In this study, a cross-sectional method, using a convenience sampling approach, was adopted to collect the data of 191 caregivers of cancer patients who were referred to the oncology clinic and cancer institute of hospitals affiliated with Tehran University of Medical Sciences, Iran. The participants completed a questionnaire on basic demographics, the short version of the Burden Scale for Family Caregivers, and Zimet Multidimensional Perceived Social Support. A maximum likelihood exploratory factor analysis with oblique rotation to assess the factor structure of the constructs and the measurement model was conducted. The two-factor model consisting of 22 items explained 65.116% of the variance. There was a significant negative relationship between social support and burden (b = −0.771, P < 0.001) and also between economic status and burden (b = −0.308, P < 0.01). Moreover, there was a significant positive association between the interaction of social support and economic status and burden (b = 0.138, P < 0.05). More specifically, the negative relationship between social support and burden was statistically stronger for participants with weak economic status (b = −0.663, P < 0.001) than those with good economic status (b = −0.356, P < 0.01). Social support and an individual’s economic status are essential determinants of caregiver burden. Further studies are recommended to better inform the precise support needed by caregivers to enhance their quality of life, and ultimately, that of the patients under their care.