The hierarchy problem---the seventeen-order-of-magnitude separation between the electroweak scale and the Planck scale---remains one of the most compelling open questions in theoretical physics. Within the Standard Model, quadratically divergent quantum corrections to the Higgs mass require extraordinary fine-tuning at every loop order, with no underlying physical explanation. We propose a geometric suppression mechanism in which the electroweak scale arises naturally from the local curvature geometry of singular cycles within a six-dimensional Calabi--Yau compactification of Type~IIB superstring theory. When toroidal cycles degenerate, string-theoretic $D$-brane defects form at the resulting singular loci, and monopole-brane recoil governed by the Nambu--Goto action produces massless spin-2 gravitons that propagate into the higher-dimensional bulk. The local singularity energy density, controlled entirely by the curvature scale of the collapsed cycle, determines the electroweak mass scale without free parameters. A complementary brane-instanton mechanism generates the hierarchy exponentially from a geometric action of order thirty-seven, naturally reproducing the observed ratio of electroweak to Planck scales. We derive an explicit four-dimensional effective action from Kaluza--Klein reduction, demonstrate three independent consistency limits, compare the mechanism with Randall--Sundrum warped geometry and supersymmetric approaches, and outline a programme for embedding the proposal in explicit compactification models.