Cancer remains a public health concern worldwide, with its incidence increasing worldwide and expected to continue growing during the next decades. The microbiome has emerged as a central factor in human health and disease, demonstrating an intricate relationship between the microbiome and cancer. Although some microbiomes present within local tissues have been shown to restrict cancer development, mainly by interacting with cancer cells or the host immune system, some microorganisms are harmful to human health and risk factors for cancer development. This review summarizes the recent evidence concerning the microbiome and some of the most common cancer types (i.e., lung, head and neck, breast, gastric, colorectal, prostate, and cervix cancers), providing a general overview of future clinical approaches and perspectives.