MicroRNAs (miRNAs/miRs) have become fundamental to modern cancer diagnostics and treatment, as they can regulate the expression of various genes, and their dysregulation can lead to several cancers. This book chapter integrates recent findings on miRNAs, highlighting their importance in diagnostic, prognostic, and therapeutic advancements in oncology and cancer biology. This chapter also delineates the dysregulation of miRNAs and its implications in the initiation and the progression of different cancers. In line with these insights, emerging technologies including long-read sequencing, single-cell sequencing, and next-generation sequencing have significantly strengthened the detection platforms that aid in the high-resolution profiling of miRNA expressions. Sensors and devices driven by nanotechnology offer increased sensitivity and specificity using materials such as graphene, carbon nanotubes, and gold nanoparticles. The CRISPR-based detection platforms, notably, the CRISPR-Cas13 system have enabled researchers to accurately and rapidly detect the miRNAs through fluorescence and electrochemical techniques. Biomarker discoveries have benefited from machine learning and artificial intelligence (AI) algorithms, enabling rapid characterization of complex miRNA expression patterns. The adoption of non-intrusive liquid biopsy technologies and exosomal miRNA profiling has substantially improved the early cancer detection using the circulating miRNA levels in blood, saliva, and urine. Portable point-of-care (PoC) diagnostic tools, such as microfluidic chips and smartphone-integrated biosensors, have expanded easy, cheap and rapid access to technologies for clinical applications. Collectively, these multidisciplinary strategies have significantly strengthened the clinical utility of miRNA-based technologies in cancer, improving the diagnosis, prognosis, treatment, and personalized cancer management.