In this study, a novel flame retardant ammonium tetrafluoroborate (ATFB) was successfully synthesized using boric acid (H 3 BO 3) and ammonium hydrogen difluoride (NH 4 HF 2) as the reactants. In addition to ATFB, aluminum hydroxide (Al(OH) 3) was used as a flame retardant and red mud (RM) waste was used as a filler to prepare epoxy composite materials with enhanced flammability properties. The appropriate ratio of RM:ATFB:Al(OH) 3 both in terms of combustion and mechanical properties was found to be 15:10:5 wt%. The tensile strength of the composite in this ratio was obtained as 112 MPa, while the neat ER was 46 MPa. The burnout of the composite with the appropriate RM:ATFB:Al(OH) 3 ratio decreased in the first 10 seconds, and extinguished in 32 seconds. Moreover, the burned area of this composite was the smallest among all the others. The experimental and estimated LOI values for this composite was found as 26 and 29, respectively.