Currently, organic–inorganic hybrid lanthanide-incorporated polyoxometalates (POMs) have emerged as a prominent research area. Herein, we employed a simple raw material assembly method to synthesize two neoteric mixed-organic -ligand-ornamented lanthanide (Ln) incorporated selenotungstates [H₂N(CH₃)₂]₁₆Na₂ [Ln₄(H₂O)₆(HPZDA)₂(HFMA)₂W₈O₂₁][B-α-SeW₉O₃₃]₄·29H₂O (Ln = Sm³⁺ (1), La³⁺ (2); H₂PZDA = 2,3-pyrazine dicarboxylic acid, H₂FMA = fumaric acid). 1 and 2 are isomorphic with the polyanions constructed from four trivacant Keggin [B-α-SeW₉O₃₃]^8– ({SeW₉}) segments and a rigid-flexible-ligand-ornamented dodeca-nuclear W–Ln heterometallic [Ln₄(H₂O)₆(HPZDA)₂(HFMA)₂W₈O₂₁]¹⁴⁺ cluster. Moreover, the solid-state fluorescence spectrum of 1 at room temperature mainly exhibits the characteristic emission peak of Sm³⁺ cations. Additionally, energy transfer from {SeW₉} to Sm³⁺ ions in 1 has been demonstrated by time-resolved spectroscopy. This work presents a feasible dual-ligand synergistic strategy for constructing novel POM derivatives and POM-based fluorescent materials.