Four tridentate europium(III) complexes containing a diphenylphosphoryl group are prepared with strong bonding between the ligands and centered ion, convinced by crystal structures. Compared to their parent bidentate complexes, the tridentate complexes display improved and exceptionally high photoluminescence quantum yields (PLQYs) in powder (all over 80%, best 91%), as well as in a CH2Cl2 solution and poly(methyl methacrylate) films, benefiting from compact, stable, and saturated coordination.