Electrospinning has been considered as a versatile fiber fabrication technique due to its enormous potential to develop polymeric membranes for diverse categories of applications. Modification of bulk and surface properties of electrospun membranes are considered as an effective strategy to design novel synthetic materials with improved properties. Manipulation of surface properties of the membranes by physical and chemical means is an emerging area. The primary emphasis of the review is on a critical evaluation and categorization of post-electrospinning modification techniques in the context of improving membrane performance. It includes both physical (plasma treatment, physical vapour deposition, thermal treatment and ultrasonication) and chemical methods (grafting, oxidation, hydrolysis, cross-linking, aminolysis and acid treatment) of modifications. Additionally, the current progress on click chemistry and radical initiated grafting (ATRP, RAFT and photochemical grafting) techniques for decorating membrane surface are also discussed. A comprehensive evaluation of the relative advantages and disadvantages of different post-modification strategies are provided in detail. The recent advances in applications of modified electrospun membranes for biomedical and water filtration applications are extensively summarized.