A light filament (206) formed from carbon nanotubes is characterized by high mechanical strength and durability at elevated temperatures, a high surface area to volume ratio, and high emissivity. Additionally, electrical resistance of the light filament does not increase with increasing temperature as much as electrical resistance of metallic light filaments. Accordingly, power consumption of the light filament is low at incandescent operating temperatures. A method for making a light filament made of carbon nanotubes includes the steps of: forming an array of carbon nanotubes (20); pulling out carbon nanotube yarn (204) from the carbon nanotube array; and winding the yarn between two leads (30) functioning as electrodes to form the light filament.