Fixed and Floating Offshore structures commonly utilize I-beams as structural components withstanding distributed loads on their decks or inside hulls. These structural members get damaged due to the corrosive marine environment leading to a condition in which they need replacement or rehabilitation. Such situations are not desirable as it will incur monetary losses directly with replacement or repair costs and indirectly through operational losses due to shut down for hot repair works. A safe and economical alternative for structural rehabilitation of damaged I-beams is using Fibre Reinforced Polymer (FRP) composites. An experimental investigation on the feasibility of repair of a heavily damaged I-beam using two different types of FRPs is presented. The severe damage in the I-beam was artificially introduced by removing both flanges and the web for 300 mm in the mid-span of 1800 mm long I-beam. Four-point bending tests under static loads were performed until failure of the beam. The first repair was done using carbon fibre reinforced polymers (CFRPs) and the second one utilized glass fibre reinforced polymers (GFRP). The CFRP repaired specimen showed 277% improvement from the damaged state whereas the GFRP repair improved 248% in terms of the ultimate strength. A comparison of the behaviour between CFRP and GFRP repair is also highlighted in the study. Various parameters like stiffness, ductility, load-displacement behaviour and failure modes of these FRP repairs for damaged I-beams are discussed in detail. Overall, the results from the study portray the adequacy of an FRP rehabilitation to reinstate the strength from such structural damages in I-beams.