Fabrication of highly ordered arrays of single-walled carbon nanotubes (SWNTs) has been of great interest for a wide range of potential applications. Here, we report thermally switchable one- and two-dimensional arrays of individually isolated SWNTs formed by cooperative self-assembly of functionalized SWNTs and a block copolymer/water system. Small-angle X-ray scattering measurements reveal that when the block copolymer/water system is in an isotropic phase, two-dimensional hexagonal arrays of SWNTs are formed by depletion attraction, and when the block copolymer/water system is in a lamellar phase, one-dimensional lattices of SWNTs intercalated in the polar regions of the polymeric lamellar structure are formed by entropically driven segregation and two-dimensional depletion attraction. These two SWNT arrays are thermally interchangeable, following the temperature-dependent phase behavior of the block copolymer/water system.