Infecting about half of the world´s population, is one of the most prevalent bacterial infections worldwide and the strongest known risk factor for gastric cancer. Although colonizes exclusively the gastric epithelium, the infection has also been associated with various extragastric diseases, including colorectal cancer (CRC). Epidemiological studies reported an almost two-fold increased risk for infected individuals to develop CRC, but only recently, direct causal and functional links between the chronic infection and CRC have been revealed. Besides modulating the host intestinal immune response, is thought to increase CRC risk by inducing gut microbiota alterations. It is known that infection not only impacts the gastric microbiota at the site of infection but also leads to changes in bacterial colonization in the distal large intestine. Considering that the gut microbiome plays a driving role in CRC, infection emerges as a key factor responsible for promoting changes in microbiome signatures that could contribute to tumor development. Within this review, we want to focus on the interplay between infection, changes in the intestinal microbiota, and intestinal immunity. In addition, the effects of antibiotic eradication therapy will be discussed.