This comprehensive chapter paper delves into the multifaceted realm of β-glucans in mushrooms, shedding light on their immunomodulatory and anticancer effects. We explore how β-glucans interact with the immune system, stimulating both innate and adaptive immune responses. Moving forward, we delve into the anticancer potential of β-glucans, encompassing their impact on cancer cell growth, apoptosis, and angiogenesis. We discuss the synergy between β-glucans and conventional cancer therapies, highlighting the promise of combining these compounds with existing treatments. Moreover, this chapter delves into the clinical evidence supporting the immunomodulatory and anticancer effects of β-glucans, elucidating their role as potential adjuvants in cancer therapy. We scrutinize the various mushroom species rich in β-glucans and the differences in their β-glucan profiles, emphasizing their implications for healthcare. Additionally, we analyze factors influencing β-glucan content and bioactivity, including mushroom species, cultivation methods, and processing. The cultivation and extraction techniques aimed at optimizing β-glucan content are scrutinized, promising enhanced bioactivity and therapeutic potential. Furthermore, we explore the safety of β-glucan consumption and potential adverse 104effects. As we conclude, we provide insights into future research directions, including the need for more extensive clinical trials and a deeper understanding of the synergistic effects of β-glucans with other therapeutics. This chapter synthesizes the vast body of knowledge surrounding β-glucans in mushrooms, underlining their role as a burgeoning frontier in immunomodulation and cancer therapy, offering a glimpse into the possibilities of harnessing nature's compounds for human well-being.