Informal caregivers' own quality of life, health status, and determinants are poorly understood despite their concern for the health of the individuals they assist. To compare the quality of life and the health determinants of older informal caregivers with those of older adults without caregiving responsibilities. An online survey was designed to investigate the quality of life and the health determinants of people aged 65 years and over, with a focus on informal caregivers. In addition to socio-demographic data, the number of informal caregivers was ascertained and the Zarit scale of caregiver burden was applied. Quality of life (SF-12) and health determinants (access to technology and level of physical activity (IPAQ)) were assessed and compared between informal caregivers and non-caregivers. A total of 111 participants were included in the study (70 ± 3.83 years, 71.2% women). The majority of respondents (91.8%) were Belgian. One-third of the respondents identified themselves as informal caregivers and declared themselves as having a severe burden (61.9 ± 15.2/88). Socio-demographic characteristics and access to technology were similar between informal caregivers and non-caregivers (p > 0.05). However, informal caregivers had a lower SF-12 score in the mental score domain (44.3 ± 10.2 vs. 50.7 ± 7.0; p = 0.004) and a lower level of physical activity (434 ± 312 METS/min/week vs. 1126 ± 815 METS/min/week; p = 0.01) than their peers. Informal caregivers reported a lower quality of life and a lower level of physical activity than their peers. Given the recognized importance of physical activity for overall health, this survey highlights the need to promote physical activity among older informal caregivers.