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Our recent experimental investigations into the hP12 phase of WB2 revealed that WB₂ superconducts above 50GPa with a maximum superconducting critical temperature Tc of 17 K at 90 GPa. High-pressure resistivity and XRD measurement revealed no structural phase transition. Calculated electron-phonon T_c for the hP12 phase fails to explain the observed superconductivity. In this talk, we present theoretical evidence that the formation of planar defects at high pressure explains the observed superconductivity. Enthalpy calculations indicate that stacking faults and twin boundaries can form during plastic deformation of the hP12 WB₂ phase at high pressure. Furthermore, the atomic arrangement at these planar defects resembles the arrangement of atoms in the MgB₂ P6/mmm structure. Our electron-phonon coupling calculations show that P6/mmm WB₂ has the highest T_c among the competing phases and this phase is thermodynamically stable above 130GPa. The formation of planar defects is also consistent with the observed change in c/a ratio above about 50 GPa. Thus, the formation and percolation of mechanically induced stacking faults and twin boundaries lead to filamentary superconductivity in WB₂ at high pressure. Our results may lead to an alternate route for designing superconducting materials.