Background and Objective <p>This review aimed to synthesise evidence from micro-costing studies of laboratory-based genetic and genomic testing in oncology by identifying the resource components, critically examining measurement and valuation methods, determining key cost drivers, and assessing the overall quality and transparency of existing published studies to inform more comparable cost estimation practices.</p> Methods <p>Four large electronic databases, PubMed, SCOPUS, Web of Science, and Cumulative Index of Nursing and Allied Health Literature (CINAHL) were searched and restricted to articles published from 2005 to October 2024. The extracted data from the included studies were synthesized and presented in tables covering study characteristics, direct costs (including resource identification, measurement, and valuation), and cost parameters. Cost estimates were adjusted and converted to 2024 US dollar values. The results were narratively synthesized due to the inapplicability of meta-analysis. The quality of the included studies was assessed with the use of a modified version of the Consensus on Health Economic Criteria (CHEC) Checklist.</p> Results <p>This review synthesized data from nine eligible studies. All the included studies were from high-income countries. Results demonstrated inconsistent reporting of both the direct and indirect costs. There was also a significant variation in how the researchers identified, measured and valued the costs of labour, equipment, and supplies. The cost of cancer genetic and genomic testing ranged from $76.91 to $11,431.66, with whole exome sequencing (WES) and whole genome sequencing (WGS) being the most expensive options.</p> Conclusions <p>Although most studies scored highly on the modified CHEC checklist, it is important to improve in standardization for the future quality of micro-costing research. Specifically, developing uniform terminology, clear guidelines for laboratory workflows, and frameworks for identifying, measuring, and valuing cost components is critical. The establishment of a standardized micro-costing guideline or framework is essential to address these issues. The availability of accurate and high-quality cost data would enable policymakers to make informed decisions regarding the establishment, implementation, and expansion of genetic and genomic testing services across various healthcare settings and countries.</p> Trial Registration <p>PROSPERO CRD42024586802.</p>