A greener approach was applied for gold nanoparticles (AuNPs) synthesis via simple, non-hazardous and environment-friendly route utilizing the fruit peel extract of Manilkara zapota (sapodilla). The phytochemical screening of peel extract revealed that this extract act as a reductant and stabilizer concurrently for surface-functionalized AuNPs synthesis. The UV-Vis spectroscopy, FTIR, XRD, SEM-EDX and HR-TEM were employed to confirm the fabricated AuNPs. Moreover, a proficient fluorescence approach for the determination of thiourea (TU) based on fluorescence resonance energy transfer between rhodamine B (RB) and synthesized AuNPs, promotes fluorescence quenching. On addition of TU, the fluorescence of RB was recovered due to competitive adsorption between thiourea and RB on the surface of AuNPs, Which induces further aggregation of AuNPs. In optimal state, the linear relationship between the fluorescence recovery efficiency and TU concentration with the linear range from 0.02 − 1.0 ppm and the calculated detection limit was 0.017 ppm. The proposed fluorometric method was effectively utilized for TU detection in the actual sample with a good recovery percentage.