Conventional grain-oriented silicon steel (GO) relies on AlN/MnS-type inhibitors and long purification anneals, which increase alloy design complexity, energy consumption and cost. This study establishes a dislocation-loop-induced secondary recrystallization route in Fe-3 wt.% Si grain-oriented silicon steel produced by twin-roll strip casting with rare-earth Y microalloying. Steels containing 0, 0.05 and 0.1 wt.% Y were cold-rolled to 0.30 mm and subjected to primary and secondary recrystallization annealing. Electron backscatter diffraction (EBSD) reveals that 0.05 wt.% Y promotes {100}-oriented columnar solidification grains and strengthens the surface {111}⟨110⟩/{111}⟨112⟩ γ-fiber after rolling, increasing shear-band density and Goss nucleation sites while refining the primary-recrystallized matrix. Transmission electron microscopy shows abundant, thermally stable ⟨100⟩ dislocation loops (~50–100 nm) in Y-containing steels, rather than the commonly reported 1/2⟨111⟩ loops. These ⟨100⟩ loops act as effective grain-boundary pinning centers, suppressing normal grain growth and triggering abnormal Goss growth during high-temperature annealing. The 0.05 wt.% Y steel attains a secondary-recrystallization fraction of ~70%, with B₈ = 1.71 T and P_1.7/₅₀ = 2.81 W·kg⁻¹, whereas the Y-free alloy exhibits only normal grain growth and a weak Goss texture; excessive Y (0.1 wt.%) over-suppresses boundary mobility. The strong Y–vacancy affinity rationalizes the formation, thermal stability and potential recyclability of ⟨100⟩ loops, providing an inhibitor-free, energy-efficient pathway for manufacturing high-performance grain-oriented silicon steel.