Extensive research has been devoted to the chemical manipulation of carbon nanotubes. The attachment of molecular fragments through covalent-bond formation produces kinetically stable products, but implies the saturation of some of the C-C double bonds of the nanotubes.[1] Supramolecular modification maintains the structure of the SWNTs but yields labile species.[2] Here, we present a strategy for the synthesis of mechanically interlocked derivatives of SWNTs (MINTs).[3] In the key rotaxane-forming step, we employed macrocycle precursors equipped with two recognition units and terminated with bisalkenes that were closed around the nanotubes through ring-closing metathesis. The mechanically interlocked nature of the derivatives is probed by analytical, spectroscopic, and microscopic techniques, as well as by appropriate control experiments.[4,5] Remarkably, bulk reaction data confirm the interlocked nature of MINTs.[6] Comprehensive photophysical, electrochemical and theoretical characterization experiments indicate that the formation of MINTs goes hand in hand with distinct effects on the physical properties of both the carbon nanotubes and the macrocycles, clearly different from what is found in non-interlocked supramolecular references. The changes affect fundamental properties, such as solubility, diffusion coefficient, and electronic interaction between macrocycles and nanotubes.[7]