MicroRNAs (miRNAs) are key molecules that regulate gene expression. miRNAs regulate protein synthesis by binding to mRNA, influencing processes such as cell proliferation, metastasis, and apoptosis. They play a pivotal role in cancer development. Current research mainly explores miRNA mechanisms and applications, and the techniques underpinning this research are foundational to both basic science and clinical translation. However, no review has comprehensively examined miRNA mechanisms and applications from a technical perspective, creating a need for this work. Advances in RNA sequencing technology, CRISPR/Cas9 technology, and bioinformatics tools have deepened our understanding of miRNA interactions. miRNA can serve as a biomarker for cancer diagnosis and prognosis, with significant clinical potential. The development of miRNA mimics and inhibitors has brought new hope for cancer treatment, especially in reversing cancer drug resistance. This article reviews the vital role of miRNA interactions in cancer occurrence, development, diagnosis, and treatment, providing new perspectives and strategies for personalized medicine and cancer therapy.