Discovering innovative metal-oxo cluster materials with uncommon building blocks and exploiting their application potentiality are fairly challengeable. Here, we provide a novel type of lanthanide-incorporated polyoxometalates [H2N(CH3)2]10Na8H6{[Ln0.5/Na0.5(HGCA)(H2O)1.5]2[(BiO3)(SeO3)2W21O66]2}·36H2O [Ln = Eu3+ (1), Er3+ (2), H2GCA = α-glycolic acid] synthesized by a dual-heteroatom-directed synergetic strategy, which are established from two unique BiIII-SeIV heteroatom-oriented cylindrical three-layered [(BiO3)(SeO3)2W21O66]13- cage clusters integrated by lanthanide-organic groups. Compound 1 works as a fluorescence probe for high-sensitivity detection toward a neurotransmitter dopamine. This finding not only shows the enormous possibility and feasibility to create novel polyoxometalate building units by means of the self-categorization of different heteroatoms, which are subsequently employed for further assembly chemistry, but also provides a platform to exploit latent utilizations of polyoxometalate-based materials in the realm of detecting biological molecules.