Composites of photocatalysts such as titania (TiO₂) and various carbon allotropes such as carbon nanotubes (CNTs) are being extensively explored because of enhanced visible light response resulting from interfacial bonding between photocatalysts and carbon that extends light absorption bandwidth and reduces recombination of photogenerated carriers through efficient interfacial charger transfer. We have developed highly visible-light photoactive composites comprised of anatase-TiO₂ nanoparticles decorated on single-wall CNT (SWCNT) aerogels (TiO₂/SWCNT). SWCNT aerogels are three-dimensional, highly porous network of isotropically oriented SWCNTs. We used X-ray photoelectron spectroscopy to establish interfacial bonding between TiO₂ and SWCNTs mediated through Ti–C and Ti–O–C bonds, narrowing the absorption edge to ≈ 2.4eV as confirmed by absorbance spectroscopy and greatly reducing the interfacial resistance as corroborated by electrochemical impedance spectroscopy, giving rise to visible-light photoactivity. The composites rapidly degrade methylene blue dyes at a rate of 56 μmol/h/g and exhibit a high photocurrent density of 80 μA/cm² under visible-light. In contrast, composites prepared by mechanically mixing TiO₂ and SWCNTs exhibit no photoactivity in the visible-light and only slight photoactivity in the white-light. Moreover, transformation of TiO₂ from anatase to rutile phase lead to a reduction in the Ti–O–C bonds, likely during crystal structure reorganization associated with anatase-to-rutile phase transformation, markedly decreasing the dye degradation rate and photocurrent density in visible-light by ≈ 50%. Our work demonstrates the impact of interfacial bonds on emergent visible-light photocatalytic response of TiO₂/SWCNT heterogeneous photocatalysts and provides guidance in designing new heterocatalysts based on SWCNT aerogels for efficient solar energy conversion. This work has been partially supported by the NSF through Grant CMMI 1335417.