Birefringent materials play a crucial role in light polarization, with important applications in fiber-optic communications. However, developing such materials for the solar-blind region and shorter wavelengths remains challenging due to the inherent trade-off between birefringence and bandgap. In this work, we introduce a strategic assembly of cyanuric rings with biuret units—the latter identified for the first time as a birefringence-active motif—resulting in two new compounds: [H₅C₂N₃O₂][H₃C₃N₃O₃] (1) and [H₅C₂N₃O₂][H₃C₃N₃O₃]·xH₂O (x ≈ 0.43) (2). Through hydrogen bonding-driven structural optimization, compound 2 achieves a 50% increase in birefringence (Δn = 0.403 @ 546 nm) compared to 1, while retaining a short cutoff edge of 208 nm. This advancement demonstrates that hydrogen-bond-guided structural design, combined with novel functional units, can overcome the traditional birefringence-bandgap conflict, opening new possibilities for short-wavelength birefringent materials with strong optical anisotropy.