High-temperature Raman spectroscopy has been applied to investigate the melt structure near the BiB₃O₆ (BIBO) crystal–melt interface. Based on the experimental results, the crystal growth mechanism was proposed. (BOØ)_n (Ø = bridging oxygen atom) chains and free Bi³⁺ cations present in the BIBO bulk melt act as the crystal growth units. Bi-Ø bonds and [BØ₄]-tetrahedra were found near the BIBO crystal–melt interface. Two neighboring oxygen atoms in a (BOØ)_n chain or in two different (BOØ)_n chains are connected by the Bi³⁺ cations to form the structural prototype of BIBO crystal. Two adjacent (BOØ)_n chains are further connected to each other through the [BØ₄] tetrahedra to form the BIBO crystal structure. The predicted growth habit of the BIBO crystal is consistent with the observed one based on the mechanism.