The utilisation of waste biomass in biodiesel production as a sustainable energy source can lead to theincorporation of circular bioeconomy principles in the current economic systems. Herein, we synthesiseda magnetically recyclable solid acid catalyst for the esterification of waste date seed oil. The catalystspossessed superparamagnetic behaviour and high saturation magnetisation, allowing them to be easilyseparated from the reaction mixture using an external magneticfiled. The esterification reaction wasmodelled and optimised by RSM (Design Expert program) and parametric study. The magnetic solid acidcatalyst showed high catalytic performance with 91.4% biodiesel yield with optimum conditions ofresidence time, catalyst loading and temperature of 47 min, 1.5 wt %, and 55C, respectively. The solidcatalyst was easily recovered by simple magnetic decantation and reusedfive consecutive times withoutsignificant degradation in its catalytic activity. This approach of using waste date seed coupled withcheap magnetic solid acid catalyst has the potential to create more sustainable and cost-effective cata-lytic systems for biodiesel production. This will complete the full cycle of waste date seed sustainably andfacilitate the development of circular bioeconomy. The LCA results by using CML-IA baseline V3.06midpoint indicators, for 1000 kg of biodiesel production showed the cumulative abiotic depletion offossil resources over all the processes as 19037 MJ, global warming potential as 1114 kg CO2eq, andhuman health toxicity as 633 kg 1,4-DB eq (kg 1,4 dichlorobenzene equivalent). The highest damage in allcategories was observed during catalyst preparation, and reuse, which was also confirmed in endpointLCAfindings performed using ReCiPe 2016 Endpoint (E) V1.04.