Patients with chronic pain and mental disorders constitute a huge, heterogeneous group. The study aimed to identify potential practical pain biomarkers in this patient group. Methods: The PubMed, Scopus, and Cochrane databases were examined in 2011-2021 for the availability of full-text, original research and review publications using the keywords: pain biomarkers and mental disorders, Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) were used to review the literature systematically. Results: A literature search identified 283 studies, in the subsequent selection stages, 11 studies were selected for analysis. Individual pain mediators have been distinguished, which may be markers of pain in patients with mental disorders. There are three main areas of possible use of biomarkers for the clinical assessment of pain in patients with psychiatric disorders: neuroimaging, changes in metabolite levels in body fluids, and changes in gene expression. Most of the described biomarkers found in the research are of no practical importance. The most advanced are biomarkers of body fluids. Conclusion: Research on biomarkers is a dynamically developing field. The assessment of pain biomarkers in body fluids (serum, saliva and urine) seems to be the most practical and promising method of clinical application.