A facile way to fabricate spin crossover-graphene nanocomposites has been developed, and [Fe(Htrz)₂(trz)](BF₄)–graphene (SCO-G) nanocomposites have been successfully synthesized and characterized. SEM and TEM demonstrated that [Fe(Htrz)₂(trz)](BF₄) nanoparticles (ca. 50 nm) were distributed uniformly onto the surface of the graphene. Interestingly, graphene as a substrate produced an effect on the spin crossover properties of [Fe(Htrz)₂(trz)](BF₄) nanoparticles.