A method of making a carbon nanotube composite yarn, the method including growing floating carbon nanotubes in a reactor, forming a mat of carbon nanotubes from the floating carbon nanotubes, a deposition step including depositing secondary particles on at least a portion of the mat of carbon nanotubes to provide a carbon nanotube composite mat, and a densification step including densifying the carbon nanotube composite mat to provide a carbon nanotube composite yarn.