Objective Communities' use of technology and the internet for online health information (OHI) is increasing exponentially. An understanding of how and why individuals access OHI, and how this information influences decisions on health, medicines and self-care practices is critical. This review aims to: (1) identify the factors influencing OHI-seeking behaviour; (2) evaluate the evidence of OHI on self-care practices; and (3) outline strategies to improve online informed decision-making and assess the impact of these strategies on consumer outcomes. Methods A review of systematic reviews was conducted in November of 2023, following the Cochrane Handbook and PRISMA guidelines, and using PubMed, Scopus, Web of Science and EBSCOhost databases. The methodological quality of retrieved reviews was appraised using the AMSTAR 2 tool. Results The search retrieved 1725 records. Of these, 943 were screened, and 33 were included in the final analysis. The most frequently identified reasons for seeking OHI were to retrieve diagnostic and treatment information, and well-being and emotional support. Level of education and socio-economic status influenced OHI-seeking. OHI directly influenced self-care decision-making by individuals and their relationships and communication with healthcare providers. Overall, OHI-seeking (and interventions to promote the use of OHI) enhanced individuals’ confidence, skills and knowledge. Conclusions The findings highlight the benefits of OHI-seeking and its potential influence on self-care decisions. Future research should focus on strategies that would promote the pursuit of high-quality, up-to-date OHI and on the development of interventions for healthcare professionals to improve patients’ use of OHI in self-care and self-efficacy.