Cellular senescence, often referred to simply as "senescence", is a complex intracellular process with diverse biological, physiological, and pathological roles. Biologically, it is essential for embryogenesis and development. Physiologically, senescence acts as a safeguard against tumorigenesis by preventing the proliferation of damaged or defective cells. However, persistent activation of senescence can contribute to various pathological conditions, particularly those associated with aging, cancer, and other chronic diseases such as liver and pulmonary diseases. Growing evidence links aging to heightened activation of cellular senescence, leading to the accumulation of senescent cells. Here in this perspective, we aim to decipher the latest molecular mechanisms and regulatory pathways of cellular senescence in the context of aging and aging-related diseases. Additionally, we discuss emerging research directions, highlighting current limitations and gaps in the field. Addressing these challenges may not only advance our understanding of senescence but also uncover new therapeutic opportunities.