Compared with the ripple of visible Eu^III-based emission intensity induced by appended [Fe^IIN₆] spin crossover (SCO) units, as detected in the triple-stranded [EuFe(L1)₃]⁵⁺ helicate, the lanthanide-based luminescent detection of Fe^II spin-state equilibria could be improved significantly if the luminophore emission is shifted toward the near-infrared (NIR) domain. Replacing Eu^III with Nd^III in [NdFe(L1)₃]⁵⁺ (i) maintains the favorable SCO properties in acetonitrile (critical temperature T_1/2 = 322(2) K), (ii) saturates non-radiative vibrational relaxation processes in the 233-333 K range and (iii) boosts the crucial intramolecular Nd^III → Fe^II energy transfer rate processes which are sensitive to the spin state of the Fe^II metallic center. Consequently, the steady-state near-infrared (NIR) Nd(⁴F_3/2 → ⁴IJ) emission of the luminophore is amplified and linearly correlated with the LS-[Fe^IIN₆] and HS-[Fe^IIN₆] mole fraction controlled by the SCO equilibrium. This paves the way for a straightforward and direct NIR luminescent reading/sensing of Fe^II spin state in single molecules.