H19 is a long non-coding RNA (lncRNA) molecule that is encoded by the H19 gene located on chromosome 11 in humans and is exclusively expressed from the maternal allele. H19 is involved in the regulation of various cellular and biological processes, including embryonic development, cell growth, and differentiation. The H19 gene has been implicated in cancer development and progression, as it has been found to be dysregulated in a variety of cancers, including breast, liver, lung, and bladder cancer. Critically, H19 has been reported to act as both an oncogene and a tumor suppressor, indicating that its role in cancer is multifaceted and varies depending on the type of cancer and the specific cellular context. In addition to its biological functions, H19 is a key biomarker, potentially laying the groundwork for the implementation of treatment modalities in cancer as well as other age-related diseases. Despite significant progress in understanding the molecular mechanisms and functions of H19, much remains to be learned about its role in disease pathogenesis and potential therapeutic applications. This review provides an overview of the current knowledge about H19 lncRNA and its biological functions and discusses its potential as a therapeutic target for various cancers.