South Korea remains one of the few Organization for Economic Cooperation and Development countries without a statutory paid sick leave system or a public sickness benefit program. This paper examines the necessity of introducing statutory paid sick leave in South Korea and outlines key considerations for its implementation. The “right to rest when sick” is a fundamental health and labor right that ensures workers can recover from illness without risking job loss or income insecurity. A comparative review of international systems demonstrates that most countries have institutional mechanisms to support workers during non-work-related illnesses or injuries through paid sick leave and/or sickness benefits. In contrast, South Korean workers—especially those in small workplaces or non-regular employment—face limited access to such protections. The absence of these systems exacerbates social inequality and increases the risk of presenteeism and delayed medical care. Introducing statutory paid sick leave is not only a public health investment but also a measure to promote labor rights, reduce productivity losses, and prevent poverty caused by illness. The implementation of such a system must ensure universal coverage, prohibit employer retaliation, and be integrated with future sickness benefit programs to create a comprehensive social safety net.