To enhance the bonding capability between recycled concrete aggregate (RCA) and paste, an innovative carbonation method was developed to modify the surface characteristic of RCA by promoting the formation of needle-like aragonite using accelerated carbonation in Mg(NO3)2 solution under an elevated temperature (75 °C). The evolution of surface microstructure, phases and reaction kinetics was investigated using multiple testing methods including scanning electron microscopy, nanoindentation, X-ray diffraction, etc. The results revealed that reactive urchin-like RCA could be prepared within less than an hour after exposing to CO2. The urchin-like wrapping with a thickness of about 100 μm was seen rapidly grown on the surface of RCA, consisting of an outermost layer of aragonite coating, a thin layer of brucite and a silica-rich layer. The mineral wrapping induced by carbonation significantly modified the roughness, topography and geochemistry of RCA's surface entirely, contributing to enhanced bonding strength between RCA and new mortar (33.54%).