Summary: Vaccine adjuvants are substances that enhance the immunogenicity of antigens and promote the production of a stronger, longer-lasting immune response. Adjuvants are an indispensable element of modern vaccinology, strengthening and directing the immune response to subunit antigens. This article focuses on the achievements of the last decade (2014–2025), introducing the topic from the historical concept of the antigen "deposit effect" to the precise activation of innate immune pathways. Four key classes of adjuvants are discussed in detail: aluminum salts, whose action strongly correlates with inflammasome activation; emulsion systems (MF59, AS03), which effectively recruit immune cells and allow for a reduction in antigen dose; and pattern recognition receptor (PRR) agonists, such as oligodeoxynucleotides and monophosphorylated lipid A, which are key to eliciting a Th1 response; and novel, complex saponin adjuvants, such as (PRRs), such as oligodeoxynucleotides and monophosphorylated lipid A, which are crucial for eliciting a Th1 response, and novel, complex saponin adjuvants, e.g., AS01, which elicit both humoral and cellular responses in populations that respond poorly to vaccination, such as the elderly. The safety of adjuvants was discussed, which, although they may increase the incidence of mild local reactions and transient systemic symptoms, do not lead to a significant increase in the incidence of serious AEFIs. Future research directions include the development of new adjuvants for “difficult pathogens” (tuberculosis, HIV, malaria, RSV, coronaviruses) and advanced immunological solutions (triggering a targeted Tfh cell response, achieving local mucosal immunity associated with the production of secretory IgA).