This study presents the characterization and thermal kinetic analysis of LDPE/carbonation sludge composites with different weight fractions (10%, 20%, 30%, 40% and 50%). Tensile, Young's modulus, hardness, morphological, thermal stability, flame retardant and dynamic mechanical properties of the produced LDPE/carbonation sludge composites were evaluated and compared. Analysis results revealed that the incorporation of calcium carbonate-based industrial waste into the LDPE matrix decreased tensile strength by 27.6%, while Young's modulus and hardness enhanced by 101.67% and 23.8%, respectively. A remarkable enhancement in both storage (E-i) and loss (E-ii) modulus were observed for LDPE/carbonation sludge composites compared to LDPE polymer. Furthermore, a significant improvement was noticed in the properties of composites containing 50% carbonation sludge due to the efficient dispersion and interface interaction between LDPE and carbonation sludge. Although the LOI value increases from 16 to 21% with the addition of waste, it is not sufficient in terms of flame retardant. For the thermal kinetic analysis, Coast-Redfern integral method was applied to three thermal decomposition zones of the composites. Accordingly, E-a and A values in zone II are higher than in zone I and III for all reaction models of composites. Overall, LDPE/carbonation sludge composites exhibited better thermal stability and dynamic properties than LDPE polymer.