This study aimed to investigate the relationship between sociodemographic characteristics, depressive symptomatology, mobile phone ownership, and different uses of WhatsApp among older adults enrolled in primary care clinics in Guarulhos, São Paulo State, Brazil. This is a secondary data analysis, using data collected in the screening of participants to be included in the PROACTIVE cluster randomized trial. Individuals aged ≥ 60 years, registered in primary care clinics in Guarulhos, were assessed for sociodemographic characteristics, depressive symptoms according to the PHQ-9, mobile phone ownership, and use of WhatsApp. We performed multiple logistic regression models to investigate characteristics of the potential users of digital interventions. Of 3,356 older adults screened for depression, 45.7% said they use WhatsApp to receive/send messages. In the subsample that presented depressive symptomatology (n = 1,020), 41.9% stated using WhatsApp. Younger older adults and those with better socioeconomic status used more WhatsApp and were more likely to own a mobile phone. Participants with higher levels of symptoms of depression were less likely to use WhatsApp. Gender, age, schooling level, income, and depressive symptomatology are variables associated with the possession of a cell phone and with the use of WhatsApp by the older adults of the sample. These findings can help to implement digital health programs better suited to disadvantaged populations in Brazil and other low- and middle-income countries through mental telehealth interventions using WhatsApp and mobile health services to the older people.