The combination of green nanotechnology and biology may contribute to anticancer therapy. In this regard, using gold nanoparticles (GNPs) as therapeutic molecules can be a promising strategy. Herein, we proposed a novel biocompatible nanogold constructed by simply microwave-heating (MWI) Au³⁺ ions and kenaf seed (KS) extract (as a reducing and supporting agent) within a minute. The pathways of gold nanoparticles (KS@GNPs) synthesis were optimized by varying KS concentration (λ_max 528 nm), gold salt amount (λ_max 524 nm), and MWI times (λ_max 522 nm). TEM displayed spherical shape and narrow size distribution (5-19.5 nm) of KS@GNPs whereas DLS recorded a Z-average size of 121.7 d.nm with a zeta potential of -33.7 mV. XRD and SAED ring patterns confirmed high crystallinity and crystalline face centred cubic structure of gold. FTIR explored OH functional group involved in Au³⁺ ions reduction followed by GNPs stabilization. KS@GNPs exposure to RAW 264.7 and NIH3T3 cell lines did not induce toxicity while dose-dependent overt cell toxicity and reduced cell viability (26.6%) was observed in LN-229 cells. Furthermore, the IC₅₀ (18.79 µg/mL) treatment to the cancer cell triggered cellular damages, excessive ROS generation, and apoptosis. Overall, this research exploits a sustainable method of KS@GNPs synthesis and their anticancer therapy. Taking all those aspects into account, our synthesized KS@GNPs still require in-depth research concerning their safe use in clinical settings.