Obesity, characterized by the excessive and abnormal accumulation of body fat, has been classified as a global pandemic by the World Health Organization (WHO). This is an increasing concern globally due to the rising incidence of obesity and its severe clinical ramifications. While obesity is traditionally linked with conditions such as type 2 diabetes and cardiovascular diseases, recent epidemiological studies have reported an association between obesity and an increased risk of various cancers. A 2019 study estimated that 3.9% of all cancer cases globally could be attributed to excess body weight (overweight, obese, or severely obese). A growing number of studies over recent years have investigated the precise causal molecular mechanisms underlying the association between obesity and cancer, yet the understanding of this complex relationship remains limited. At its core, the biological mechanisms underlying the obesity-cancer connection hinge on the alterations induced by obesity itself. These alterations encompass shifts in adipocyte function, the metabolic signaling of adipokines, and the perpetuation of chronic inflammation/oxidative stress, collectively creating a microenvironment conducive to tumor growth. Additionally, changes in insulin signaling and lipid deregulation associated with excessive adiposity may also aid in the pathogenesis of cancer. Gut microbiome changes and microenvironmental perturbations are additional mechanisms. Unraveling the intricate web of obesity-cancer nexus is essential for the identification of potential therapeutic agents targeting these shared molecular pathways. This chapter will investigate the molecular interconnections, and each of the essential pathways and mechanisms correlated with obesity and cancer. Furthermore, it will address the shared risk factors that contribute to the development of both obesity and cancer, such as a sedentary lifestyle and an unhealthy diet. It will also identify potential therapeutic targets which will aid in developing effective therapeutic strategies, spanning both personalized and population-wide approaches, that aim to reduce the risk and mortality of cancer in an increasing obese population.