Precisely quantifying the adhesion energy of delicate nanobelts on rough substrates remains challenging due to their disparate surface properties and nanoscale dimensions. To overcome these challenges, we propose an optical microscopy-based bridging method to quantify the adhesion energy of ZnS nanobelts on Si substrates in air. Our results revealed that the nanobelt–smooth substrate interfacial system exhibits an enhanced adhesion due to electrostatic interactions between the polar nanobelt surfaces and the polarized Si substrate. While, for the nanobelt–rough substrate system, adhesion energy values decreased from 0.23 to 0.10 J/m2, showing an inverse square root relationship with increasing roughness from 0.17 to 1.12 nm, deviating from the trend predicted by the parallel plate model, due to the real contact separation distance influenced by surface asperities and nanobelt–substrate conformity. Our method offers a simple and accurate approach for characterizing roughness-dependent adhesion of nanobelt–substrate systems in air, providing valuable insights for device fabrication and performance stability.