The function of biofunctionalized microscale/nanoparticles depends on the synergistic effect of the composite material composition and fine structure. However, how to achieve the controllable preparation of multiple material compositions and fine structures simultaneously and accurately in the micro–nanoscale space is still an important challenge facing functionalized microscale/nanomaterials. Microfluidics chips are made based on microfabrication technology. They can integrate multiple components and functional units on a chip, including sampling, synthesis, testing, and data acquisition modules. They can automatically analyze complex biological samples and build targeted drug treatment models. Compared with conventional preparation methods, it also has significant advantages such as low cost, portability, stable microenvironment, controllable reaction process, and high throughput. At present, microfluidic chips are used in many fields such as early cancer detection, drug and gene delivery, synthesis of micro–nanoparticles and drug carriers, cell analysis, tissue engineering, and many more. This chapter reviews the new research progress in the construction of functionalized micro–nanomaterials based on microfluidic chips and their application in tumor marker detection and tumor diagnosis and treatment, focusing on the application progress in two aspects: (1) microfluidic technology for the capture, detection, and analysis of three tumor markers in cancer liquid biopsy applications; (2) construction of functionalized micro–nanomaterials based on microfluidic chips and their application as targeted drug carriers in tumor diagnosis and treatment. It provides research references and support for researchers in related fields in the structural expansion and innovation of micro–nanofunctionalized materials, clinical application of liquid biopsy technology, integrated tumor diagnosis and treatment, and large-scale preparation of targeted drugs.