The utilisation of ethylene propylene diene monomer (EPDM) waste as a rubber matrix is one of the sustainable methods to reduce the non-degradable EPDM waste in the environment. EPDM waste in this study was devulcanised using a microwave at 600 W for 7 min before being mixed with natural rubber. Subsequently, a new rubber compound was prepared using conventional cure (CV), efficient vulcanisation cure (EV), and semi-efficient vulcanisation cure (SEV) systems, and its effect on optimum cure and scorch time and tensile properties were investigated. The percentage of devulcanisation was determined using the swelling test. Breakage of carbon–sulphur bond that indicated devulcanisation was investigated by Fourier transform infrared spectroscopy (FTIR). In addition, Thermogravimetry Analysis (TGA) curve revealed that the breakage of carbon–sulphur bonds affected the amount of EPDM weight loss during the thermal degradation study. Furthermore, the rubber compound made using CV system showed excellent tensile strength and elongation at break. Meanwhile, the EV system showed the best scorch safety time and modulus value.