In this work, we have demonstrated the successful design and bottom-up synthesis of colloidal nano-Fanowman particles exhibiting pronounced colloidal Fano dips and substantially enhanced surface-enhanced Raman scattering (Fano-SERS). By strategically employing topological Fano resonance, which independently modulates intrinsic bright and dark plasmonic modes within individual nanoparticles, we achieved exceptional optical purity, enabling the clear observation of colloidal Fano dips in ensemble spectra. Precise DNA-mediated synthetic strategies allowed quantitative control over critical nanostructural features required to robustly establish Fano resonance. Through comprehensive electromagnetic simulations-considering the excitation laser wavelength, resonant Raman dye selection, and Stokes scattering peak positions-we optimised nano-Fanowman particles yielding an average EM-EF of 7.2 × 10 7 , representing more than a 300-fold enhancement compared to resonant NNPs. Experimental results, with a measured average EF (3.2 × 10 7 ) closely matching the theoretical predictions, demonstrated remarkable average SERS enhancements (7,400-fold relative to 50-nm AuNPs and 77-fold relative to resonant Au-NNPs), despite the random orientation of nano-Fanowman particles on substrates. Furthermore, single-particle dark-field microscopy-correlated Raman measurements confirmed the outstanding performance of nano-Fanowman particles, exhibiting detectable Fano-SERS signals even at ultralow laser powers (~1 nW). Detecting SERS at such ultralow powers represents a substantial improvement compared to the tens to hundreds of microwatts typically required for single-nanoparticle SERS measurements, highlighting significant potential for noise-free detection, reduced laser-induced sample damage, and substantial reductions in analytical costs. Our findings provide a clear and robust pathway toward developing ultrasensitive, reliable, cost-effective, and broadly applicable SERS-based platforms, significantly advancing the field of colloidal plasmonics and nanophotonics.