Wavelength-selective integrated photonic devices in silicon-photonic platform require tuning to match the operating wavelength of multiple devices. The operating wavelengths are generally in the near-IR band. The conventional method of choice is to thermally tune the refractive index of silicon using metal micro-heaters. However, metals absorb near-IR wavelengths and must be placed away from the waveguides to avoid optical losses. This significantly reduces the power-efficiency of the heaters. Graphene-based local heaters on top of waveguides have been recently explored. Although the absorption in graphene is less than that of metals, it is still large enough to necessitate the placement of a thin spacer between the waveguide and the heater. We observe that metallic carbon-nanotubes (CNTs) are comparatively more transparent in the C-band. We implement heaters made of solution-processed metallic CNTs directly on top of a silicon-on-insulator micro-ring resonator. We demonstrate thermo-optic tuning of 60 pm/mW on a micro-ring resonator having a free-spectral range (FSR) of 1.75 nm. The estimated power efficiency is 29 mW/FSR, which is at par with previously implemented graphene-based heaters, that has higher absorption and better than conventional metal heaters. The proposed configuration offers compact and efficient thermal-tuner integration.