Novel homoleptic arylborane-dipyrrinatoplatinum(II) complex [Pt(B-ph-dipy)(2)] (B-ph-dipy = 5-{4-(dimesitylboryl)phenyl}-dipyrrinate) was designed and synthesized. Two stereoisomers of [Pt(B-ph-dipy)(2)] based on the coordination geometry (i.e., square-planar (1) and distorted tetrahedral (1')) were obtained and characterized. The complexes 1 and 1' showed more intense absorption than a reference complex without any arylborane substituents [Pt(ph-dipy)(2)] (2) (ph-dipy = 5-phenyldipyrrinate) in the >300 nm region. Furthermore, the emission spectrum of 1' was broad and structureless compared to the structured emission spectra of 1 and 2. The emitting excited state of 1' is ascribed to a mixed charge transfer of MLCT in the distorted tetrahedral bis(dipyrrinato)platinum(II) moiety and pi(aryl)-p(B) CT in the arylborane moieties.