<p>A series of quaternaphthalenes (QNps) containing four naphthalene chromophores were synthesized and investigated as all-hydrocarbon multi-chromophore emitters. The QNps exhibited near-UV to deep-blue fluorescence in solution and retained emission in the solid state. The negligible solvent dependence of the fluorescence spectra supports locally excited π–π* emissive states rather than intramolecular charge-transfer states. Photophysical analysis revealed that the fluorescence behavior is governed primarily by naphthalene connectivity. Several QNps, especially <b>126151</b> and <b>126261</b>, showed high fluorescence quantum yields and large radiative rate constants, whereas <b>126272</b> exhibited a smaller radiative rate and a longer fluorescence lifetime, indicating suppression of the radiative transition probability by a specific linkage topology. TD-DFT calculations showed that highly emissive QNps possess large oscillator strengths and mainly HOMO–LUMO-based S₁ ← S₀ transitions. A positive Strickler–Berg-type analysis including related ternaphthalene data further supports the relationship between topology-dependent oscillator strength and radiative dynamics, while indicating a lower <i>k</i>_f/<i>f</i> trend for 2,7-linked polynaphthalene derivatives. These results demonstrate that efficient deep-blue emission in polynaphthalene systems is achieved not by simply increasing the number of chromophores, but by optimizing the connectivity that preserves a large radiative transition probability.</p> Graphical abstract