Liver malignancies represent one of the major public health problems worldwide because of late diagnosis and failure of current treatments to offer a curative option for many of the patients. MicroRNAs (miRs) are small non-coding RNA molecules that are known to regulate the gene expression at a post-transcriptional level through complementary base pairing with thousands of messenger (m)RNAs. Recent data has shown the involvement of miRs in the pathogenesis of many human cancers, including those of the liver, with huge possible impact in the clinic, mainly due to the identification of non-coding RNAs as biomarkers that can often be detected in the systemic circulation. In the current review, we present the importance of miRs in liver cancers by discussing their role in the pathobiology of these diseases, apart from their role as diagnostic and prognostic markers for liver malignancies.