Waste product utilization for natural resource conservation in the construction and building industry is now standard practice. The study targets the behaviour of cement-stabilized fiber-reinforced Incinerated bottom ash (IBA) when tested under unconsolidated-undrained (UU) conditions. Triaxial tests were conducted on the stabilized IBA specimens with varying cement content (3–9%) and fibers (13 and 19 mm) with a variation limited from 0% to 1%. The results indicate that cement stabilization leads to the improved shear strength of bottom ash specimens, whereas the additional transformation in the performance from brittle to ductile was noted in fiber-reinforced specimens. The observed UU strength values improved with the addition of fibers and later decreased. Adding 13 mm fiber (0.5%) with 9% cement content produced the best results, with an improvement of 66.25% in strength compared to the unreinforced composites for 28 days of curing. SEM analysis of the cured specimen comments on the effect of the curing period and the experimental results. The study also aims to predict the shear strength of IBA composites using four modelling techniques: Back Propagation neural network (BP-NN), Adaptive Neuro-fuzzy systems (ANFIS), Beetle Antenna search-Random Forest (BAS-RF model), and M5P model tree. These predictions were attempted by considering fiber percentage, fiber length, cement content, and the curing period. BAS-RF and ANFIS strongly correlated to the experimental results compared to BP-NN and M5P Tree. The precision of designed models is analyzed by the Coefficient of determination, Root mean square error, and Variance accounted for.