Two iron(II) compounds with the general formula of Fe(phen‐TPE)2(NCX)2 ⋅ Y (phen‐TPE=3‐(tetraphenylethylene)‐1,10‐phenanthroline; X=S and Y=2DMF for 1 ⋅ 2DMF; X=Se and Y=DMF for 2 ⋅ DMF) were synthesized and characterized by single‐crystal X‐ray crystallography and magnetic measurements. Both compounds exhibited thermal‐induced complete one‐step spin‐crossover (SCO) behavior with the critical transition temperatures of 210 K and 260 K for 1 ⋅ 2DMF and 2 ⋅ DMF, respectively. The SCO behavior of these two isomorphic compounds depended significantly on robust intermolecular π⋅⋅⋅π interactions, NCX− groups and solvent molecules. Two ferrous compounds with aggregation‐induced emission molecule tetraphenylethylene grafted ligand and similar crystal structures have been synthesized, both showed one‐step complete spin‐crossover behaviors with different transition temperatures that mainly arose from the different NCX− groups and intermolecular hydrogen bonds.