Background: Clinical guidelines recommend psychosocial care as an integral part of medical treatment, but access is often limited. Technology-based approaches provide an attractive opportunity to optimize health outcomes and quality of life in people with chronic somatic diseases e.g. by means of Internet-and mobile-based interventions (IMIs). The present article provides an overview on the basics of IMIs, applications and their evidence base for people living with chronic somatic diseases. Methods: We conducted a selective literature search in the PubMed and Cochrane databases. Reviews which included randomized controlled trials investigating psychological IMIs were discussed pertaining to their relevance for the population described. Results: IMIs lead to a change in unfavorable behavior connected to chronic somatic diseases. IMIs can foster protective factors like balanced physical activity or risk factors like smoking or alcohol consumption. However, studies reveal small effect sizes of d=0.25 for physical activity and an averaged effect size of d=0.20 for smoking and alcohol consumption. Additionally, IMIs can be used for the (co-) treatment of chronic somatic diseases, for instance to increase disease-specific self-efficacy in patients with diabetes (d=0.23). Studies included in meta-analyses are often highly heterogenous and are investigated in research contexts with limited health care services relevance. Conclusion: IMIs are potentially effective when aiming at lifestyle changes and supporting medical treatment in people with chronic somatic diseases. However, results are still heterogenous and the evidence base is limited regarding specific settings, compounding the discussion of possible ways of implementing IMIs into our health-care systems.