Over the past two decades, optical fiber sensing technology has made considerable progress in sensor design, manufacturing process optimization, and system integration, and it has become an integral part of advanced sensing technologies. Various optical principles, such as interference, scattering, total internal reflection, and surface plasmon resonance, are applied in designing optical fiber (OF) sensors. As an emerging OF sensor device, nanostructured plasmonic OF sensors have attracted significant attention due to their superior performance and peculiar properties, realizing the Lab on fiber concept. As nanostructured plasmonic OF sensors feature the characteristics of both traditional OF sensors and plasmonic sensors, they exhibit unique advantages and can be used as powerful biochemical sensing tools or integrated photonic devices. A simple approach is also the use of metal nanoparticles in order to modify the side or end of the optical fiber to excite the surface plasmon resonance effect. One of the main branches in the "Lab on Fiber" field is optical-fiber based SERS, which seeks to combine the advantages of both SERS and optical fibers. This combination aims to create powerful, flexible, robust, and miniaturized spectroscopic tools for remote and highly sensitive detection of low-concentration molecular analytes in a variety of environments, including harsh conditions.