Direct heat welding of commonly found single-walled carbon nanotubes (SWCNTs) (i.e. diameters > 1 nm) requires a temperature of >4000 K which is too high to be practical. This work reports a novel welding method of SWCNTs at experimentally-relevant temperature by means of nanobuds to facilitate C–C bonded junction formation between the nanotubes. Through molecular dynamics (MD) simulations, it is demonstrated that SWCNTs independent of their diameters can be welded together using the proposed method even at a temperature below 1500 K.