This study examines a dual-stage process for converting pine needle biochar pyrolyzed at varying temperatures (300 degrees C, 400 degrees C, and 500 degrees C) into carbon nanotubes under microwave irradiation conditions and varying ferrocene-to-biochar ratios (1:1,1:2, and 1:3). The synthesized carbon nanotubes were characterized to evaluate their concentration, average diameter, crystalline structure, and degree of graphitization. The pine needle-derived carbon nanotubes synthesized from carbon precursors pyrolyzed at 500 degrees C demonstrated the highest degree of wall graphitization, evidenced by an ID/IG ratio of 0.86. The synthesized pine needle waste-derived carbon nanotubes exhibited average diameters ranging from 65 to 97 nm with a tubular morphology similar to that of multiwalled carbon nanotubes. These pine needle-derived carbon nanotubes were further functionalized with hydroxyl groups and used as a heterogeneous catalyst in biodiesel production from waste cooking oil. Under optimum conditions of a reaction time of 102.15 min, reaction temperature of 57.5 degrees C, methanol-to-oil molar ratio of 7.96, and catalyst loading of 1.38% wt., a maximum biodiesel conversion of 97.56% was obtained. Overall, the proposed study paves the way for sustainable utilization of waste materials such as pine needles to value-added materials and their application as heterogeneous catalysts in biodiesel production from waste cooking oil.