Saliva plays a pivotal role in shaping the oral microbiome and maintaining oral homeostasis and health. This chapter explores the importance of saliva in promoting eubiosis of the oral microbiome and its implications for oral and systemic health. Saliva is a dynamic fluid rich in antimicrobial components and buffering agents that contribute to the microbial balance and homeostasis within the oral cavity. It provides a cleansing mechanism that facilitates the removal of bacteria and debris and limits the growth and colonization of microorganisms. The salivary antimicrobial proteins and peptides, in combination with antibodies, predominantly secretory immunoglobulin A (sIgA), are crucial for combating microbial pathogens and preventing oral infections. Saliva also possesses a buffering mechanism that regulates the pH levels within the oral cavity, which creates an environment that is inimical for the growth of acid-producing pathogens and promotes remineralization of the teeth. Furthermore, salivary proteins and glycoproteins form an inter-face (tissue coat) over the oral mucosa and teeth to protect the oral tissue from external environmental insults, maintain tissue integrity, and promote wound healing. Understanding the positive role of saliva in the oral microbiome provides an insight into potential novel strategies for promoting oral health and combating microbial dysbiosis. Recognizing the multifaceted roles of saliva as a guardian (gatekeeper) of oral microbial balance, we can unlock the therapeutic potential of saliva in enhancing the well-being of the body and averting oral and systemic diseases.