Investigating the photoinduced electronic and structural response of bistable molecular building blocks incorporating transition metals in solution phase constitutes a necessary stepping stone for steering their properties toward applications and performance optimizations. This work presents a detailed X-ray transient absorption (XTA) spectroscopy study of a prototypical spin crossover (SCO) complex [Fe-II(mbpy)3](2+) (where mbpy = 4,4'-dimethyl-2,2'-bipyridine) with an [(FeN6)-N-II] first coordination shell in water (H2O) and acetonitrile (CH3CN). The unprecedented data quality of the XTA spectra together with the direct fitting of the difference spectra in k space using a large number of scattering paths enables resolving the subtle difference in the photoexcited structures of an Fe-II complex in two solvents for the first time. Compared to the low spin (LS) (1)A(1) state, the average Fe-N bond elongations for the photoinduced high spin (HS) T-5(2) state are found to be 0.181 +/- 0.003 angstrom in H2O and 0.199 +/- 0.003 angstrom in CH3CN. This difference in structural response is attributed to ligand-solvent interactions that are stronger in H2O than in CH3CN for the HS excited state. Our studies demonstrate that, although the metal center of [Fe-II(mbpy)(3)](2+) could have been expected to be rather shielded by the three bidentate ligands with quasi-octahedral coordination, the ligand field strength in the HS excited state is nevertheless indirectly affected by solvation effects that modifies the charge distribution within the Fe-N covalent bonds. More generally, this work highlights the importance of including solvation dynamics in order to develop a generalized understanding of the spin-state switching at the atomic level.