There is a high demand for life extension of offshore structures in different regions, such as Gulf of Mexico, North Sea, Malaysian and Australian waters, and etc., that are now reaching, or have exceed, their design life. An integral part of any life extension programme after assessing fitness for purpose (FFP) of the structure is strengthening, modification and repair (SMR) schemes. SMR provides a backbone to ensure structural integrity of platforms. In the context of offshore structures, however, SMR is a highly multidisciplinary engineering task requiring various skills and knowledge. This paper provides an insight on the different aspects related to this subject, from different types of offshore structures and respective loads to a comprehensive review on damages to steel offshore platforms as well as on the development in available SMR techniques. Furthermore, FFP assessment process for existing offshore platforms is briefly discussed based on the present guidelines. Finally, several gaps in the respective knowledge still needed to be addressed are introduced.