Gas-phase Bn + monocations exhibit strong hydrophilicity due to the prototypical electron-deficiency of boron. Joint chemisorption experiment and first-principles theory investigations performed herein indicate that the experimentally known planar magic-number C2v B13+ can react with H2O at room temperature to form a series of quasi-planar aromatic boron water complexes C1 B13(H2O)+ (1), C2 B13(H2O)2+ (2), and C1 B12H(H2O)+ (3) analogous to benzene C6H6. Extensive theoretical calculations and analyses unveil their chemisorption pathways, bonding patterns, and more importantly, the effective in-phase LP(H2O:)→LV(B) orbital overlaps between the more electronegative O atom in H2O as lone-pair (LP) σ-donor and periphery electron-deficient B atoms in B13+ (B3@B10+ ) and B12H+ (B3@B9H+ ) with lone vacant (LV) orbitals as LP σ-acceptors, evidencing the existence of the newly proposed boron bonds in chemistry. A LP(H2O:)→LV(B) boron bond in these boron water complexes possesses about 15 ~ 20% of the dissociation energy of a typical O–B covalent bond. Boron bonds are expected to exist in a wide range of boron-based complex systems with typical molecular ligands like H2O, CO, and NH3 as effective σ-donors.