An organic light-emitting device includes an organometallic compound represented by M1(L1)n1(L2)n2, wherein L1 is a ligand represented by Formula 1-1: In Formula 1-1, *1 to *4 indicate a binding site to M1, and Z11 and Z12 are respectively boron (B) and nitrogen (N), or N and B. When M1 binds to an α-position of the B or N atom, metal-ligand charge transfer in the complex may be improved. An OLED including the organometallic compound may have a long lifespan and improved luminescent efficiency and colorimetric purity.