The research field has recently focused on 2D structured materials because of their excellent electronic, mechanical, chemical, and optical properties. MXenes have been studied extensively in the last few years since they are a group of 2D structured materials with high electrical conductivity and mechanical strength. They are obtained by removing element ‘A’ from the parent (MAX) phase; ‘Mn+1AXn’ to ‘Mn+1XnTx’ where M is the early transition metal (Ti, Nb, Hf, V, etc.) X is carbides or nitrides, and T is the surface terminating functional group (e.g., O, F, OH, Cl). The distinct hydrophilicity, high conductivity, and adjustable surface terminations of MXenes have drawn much interest in various sectors. Hence, appropriately modifying the MXene is a better opening for multiple applications. This chapter describes the surface functionalization strategies of MXene and its improved physical, chemical, and electrochemical properties. The physicochemical properties of MXenes can be controlled by their surface chemistry, which also solves issues with MXene oxidation and dispersion stability. The environment, heat treatment temperature, and synthesis techniques all impact the surface functionalization groups. The surface chemistry of MXene can be modified by post-surface functionalization techniques or by the chemical etching procedure. Over the previous three years, porous MXenes have undergone significant design and development. Thus far, several appropriate topologies for porous MXenes have been developed using artificial procedures and applied in numerous applications, all demonstrating enhanced performance. The functional group modification by heat treatment, heteroatom doping, hybridization with polymer, and organic molecule intercalation prevent re-stacking problems and concurrently improve the through-plane ionic enhance the inherent physicochemical properties of MXene. The observed significant improvement when switching from MXene to modified MXene was attributed to the development of the electroactive area and the ion transport capabilities, supported by the morphological opening with bigger interlayer space and pores through the MXene layers. So, modified MXene is a promising candidate for improved electrochemical performance.