Acrylonitrile-butadiene-styrene (ABS) is an extensively utilized rubber-toughened amorphous thermoplastic in industry. Compared to other amorphous thermoplastics, the most promising mechanical quantity of ABS is its high impact resistance. Thus, understanding the mechanical response of ABS to multiaxial loads is of the great industrial concern. The primary objective of this study was to characterize the flexural response of ABS by conducting three-point bending tests at two distinct deformation rates of 5 and 10 mm/s to figure out the deformation rate effect on the flexural response of ABS. It was observed that the ABS act stiffer with an increased deformation rate. Numerical implementation of three-point bending tests for each deformation rate was performed using the semi-analytical material model (SAMP-1) available in Ls-Dyna finite element code. The simulations for each deformation rate were run depending on SAMP-1 and Von-Misses yield surface formulations to figure out the effect of nonidentical material behavior of ABS in tension, compression, and shear on flexural response. The percentage error in the predicted peak force values considering the compression and shear test data (SAMP-1) and without it (Von Misses) was 3% and 7% for deformation rate of 5 mm/s and 5% and 12% for deformation rate of 10 mm/s. Hence, predicting the flexural behavior of ABS accurately, dissimilar material behavior needs to be taken into consideration. Moreover, associated and nonassociated flow rule effects on the flexural response of ABS were numerically investigated and there was no significant influence observed on the flexural response of ABS.