Introduction: Engagement is essential to achieve intended outcomes of online interventions, but achieving such engagement is a key challenge for many researchers and practitioners. This systematic literature review aims to identify strategies and tools to promote the use of online health interventions for early detection and raising awareness of chronic diseases among the public, and to investigate the evidence regarding the effectiveness of such strategies. Materials and methods: We performed a systematic search of seven electronic databases: Embase, Medline All Ovid, Web of Science, Cochrane Central Register of Controlled Trials, PsycINFO, CINAHL and Google Scholar. The study protocol is registered in PROSPERO (CRD42020200471). Results: The database search identified 8,526 articles, 47 were included in the review. Thirty-two studies reported strategies to promote the use of their online intervention, including online advertisements on social media (n = 17), a dating application (n = 10), and a website (n = 3). Social media were not only used for promotion of the intervention, but also as main intervention platform (n = 18). Seven studies reported traditional promotion methods such as printed advertisement and (offline) campaigns. Twenty-seven studies reported strategies to keep users engaged, including reminders (n = 12), sharing of posts on social media (n = 4), rewards (n = 3), weekly group discussions (n = 2), follow-up phone calls (n = 2), interactive games (n = 1), monthly quizzes (n = 1), links to provision of a test kit (n = 1), and a deposit-return system (n = 1). Conclusions: No study conducted a formal evaluation of the effectiveness of the engagement strategies. Examining the effectiveness of engagement strategies is an important area for further research.