Background: Cancer is a multifaceted disorder that occurs due to abnormal cells in the body undergoing excessive growth. Although there are gaps in understanding the core reasons behind the escalation of cancers, some studies have shed light on the role that “zombie cells” play in both the emergence and development of cancer. Aged or senescent cells, more informally known as “zombie cells,” are cells that have stopped dividing but are still metabolically active. They contribute to the aging process and even the form of cancer themselves. This review specifically looks at the role of senescent cells in aging and cancer, focusing on their paradoxical nature and whether they can be selectively manipulated for treatment. Conclusion: The relationship between senescent cells and the onset of cancer is intricate and multifaceted. Senescence initially serves as a cancer prevention mechanism, but over time, the accumulation of senescent cells may contribute to the development of cancer through a number of processes. Important features of aging include chronic inflammation and age-related diseases, both of which are exacerbated by senescent cells. Targeting senescent cells and their secretory properties is a novel therapeutic strategy for the treatment of cancer and age-related diseases. Future research should focus on elucidating the specific mechanisms by which senescent cells impact cancer development and aging, as well as creating effective treatment strategies, in order to apply this knowledge for clinical applications.