Fiber optic leak detection is a highly sensitive method used to monitor pipelines. Fiber optic cables are installed along the pipeline's length, acting as continuous sensors that detect changes in the surrounding physical properties, such as temperature and pressure. DNV is a leader in verifying distributed fibre-optic sensing (DFOS) systems for pipeline leak detection. This paper reviews the existing fibre-optic sensor (FOS) technologies to suggest that these technologies have better sensing potential than traditional inspection and performance. Out of these distributed fiber optic sensing has proven to be very well suited for pipeline monitoring, as a single sensor cable can cover up to 30 kilometers of pipeline and a leak can be detected with a few meters precision.