In this study, the ultimate tensile strength (UTS), elongation (ELG) and tensile modulus (TEM) of a recycled low-density polyethylene groundnut shell fiber composite (r-LDPE/GSF) were modeled and simulated when considered particle size (PS) and fiber content (FC) of groundnut shell fiber (GSF) by applying response surface techniques (RSM) for structural application. The deposit of recycled low-density polyethylene (r-LDPE) and GSF, an agro-waste, were combined in the production of r-LDPE/GSF composite at PS of 50–70 mesh (300–212 µm) and FC of 10–30 wt% of the GSF. The manufactured r-LDPE/GSF composite was tested for UTS, ELG and TEM and optimized by considering these process variables of GSF, PS and FC with RSM. The outcome indicated that at optimum condition, the UTS, ELG and TEM were 8.5072 MPa, 12.83% and 0.94007 GPa, respectively. The parameters at this point were PS and FC of 60.48 mesh (250 µm) and 30 wt%, respectively. The coefficient of determination (R 2) was close to 0.99. The percentage of relative errors between raw experimental reading and the RSM was <0.16. Based on the result of the work, the predicted RSM data on tensile properties of r-LDPE/GSF composite shows that is a potential engineering material for structural application.