Nanoscale molecular rotors that can be driven in the solid state have been realized in Cs-2([18]crown-6)(3)[Ni(dmit)(2)](2) crystals. To provide interactions between the molecular motion of the rotor and the electronic system, [Ni(dmit)(2)](-) ions, which bear one S = (1)/(2) spin on each molecule, were introduced into the crystal. Rotation of the [18]crown-6 molecules within a Cs-2([18]crown-6)(3) supramolecule above 220 K was confirmed using X-ray diffraction, NMR, and specific heat measurements. Strong correlations were observed between the magnetic behavior of the [Ni(dmit)(2)](-) ions and molecular rotation. Furthermore, braking of the molecular rotation within the crystal was achieved by the application of hydrostatic pressure.