Full understanding of atomic arrangement in amorphous oxides both at ambient and high pressure is an ongoing fundamental puzzle. Whereas the structures of archetypal oxide glasses such as v-B2O3 at high pressure are essential to elucidate origins of anomalous macroscopic properties of more complex melts, knowledge of the high-pressure structure and pressure-induced coordination changes of these glasses has remained elusive due to lack of suitable in situ experimental probes. Here, we report synchrotron inelastic X-ray scattering results for v-B2O3 at pressures up to 22.5 GPa, revealing the nature of pressure-induced bonding changes and the structure. Direct in situ measurements show a continuous transformation from tri-coordinated to tetra-coordinated boron beginning at 4-7 GPa with most of the boron tetra-coordinated above 20 GPa, forming dense tetrahedral v-B2O3. After decompression from high pressure the bonding reverts back to tri-coordinated boron but with the data suggesting a permanent densification.