In this study, waste denim fiber (WDF) was used as a modifier to enhance the properties of bitumen incorporating tire pyrolysis oil (TPO). The designing of the experiment, analysis data, modeling and multi-objective optimization performed using response surface methodology (RSM). Base bitumen was modified with 0, 5, 10 and 15 TPO and 0, 2, 4 and 6 of WDF using high shear mixer. The interaction effects of TPO and WDF on the penetration, softening point and temperature susceptibility of bitumen were evaluated. Results showed that the addition of TPO and/or WDF has a significant effect on the consistency and temperature susceptibility of base bitumen. RSM analysis exhibited high degrees of correlation (R2) of 0.982, 0.973 and 0.947 for the dependent variables� penetration, softening point and temperature susceptibility, respectively. That indicates there is an adequate agreement between models developed by RSM and experimental results. The numerical multi-objective optimization showed that optimum properties can be achieved with 8.4 of TPO and 6 of WDF. © 2022 Institute of Physics Publishing. All rights reserved.