硼酸盐是一类含硼的化合物。当中的硼可以与三个氧原子键合成B(OR)₃，也可以与四个氧原子键合成B(OR)₄阴离子。

硼酸根离子的化学式为BO₃。它可与金属元素形成盐。在自然界中所发现的硼通常为硼酸盐矿物。硼也会与硅酸盐结合形成络合硼硅酸盐矿物例如电气石。

硼酸盐以许多形式存在。在酸和近中性的环境上，它是硼酸（通常写成H₃BO₃，但B(OH)₃更为正确）。硼酸在25°C的 pKa为9.14，硼酸虽不会在水溶液中分解，但它却是酸性，因它会与水分子产生相互作用，形成B(OH)₄：

作为典型的多元酸，硼酸（H₃BO₃）可随pH值之上升，发布氢离子，而变成H₂BO₃、HBO₃以至BO₃。

Borates are the name for a large number of boron-containing oxyanions. The term "borates" may also refer to tetrahedral boron anions, or more loosely to chemical compounds which contain borate anions of either description. Larger borates are composed of trigonal planar BO₃ or tetrahedral BO₄ structural units, joined together via shared oxygen atoms and may be cyclic or linear in structure. Boron most often occurs in nature as borates, such as borate minerals and borosilicates.