Immunoassay has been routinely used in hospitals and central labs. Nowadays, to further meet the requirement of widespread applications of immunoassays, it is urgently needed to produce a simplified, rapid and low-cost immunoassay to perform tests on site. To this end, paper-based point-of-care (POC) immunoassays have attracted intensive interests in recent years. In this paper, we present a comprehensive review of the recent advances and emerging trends of paper-based POC immunoassays, including the fundamental components and work principles, various detection mechanisms and applications, and existing commercialized devices/products. At last, we envision three promising development directions for paper-based POC immunoassays.