The US space agency said that the injector component could be made more quickly and cheaply using the technique.
The part is used to deliver liquid oxygen and hydrogen gas to an engine's combustion chamber.
The news follows General Electric's revelation that it planned to use 3D printing technology to make fuel nozzles for its jet engines.
Nasa said that California-based Aerojet Rocketdyne had made the injector using a method called selective laser melting (SLM).
The technique involves turning a computer-designed object into a real-world part by controlling a high-powered laser beam which melts and fuses thin layers of metallic powders into the preordained shape.
The test part was smaller than would be used in a full-size rocket, but large enough to test it could withstand the heat and pressure involved.
Nasa said the component would normally have taken a year to make because of the exact measurements involved, but by using SLM the manufacturing time was cut to less than four months and the price reduced by more than 70%.
"Nasa recognises that on Earth and potentially in space, additive manufacturing can be game-changing for new mission opportunities, significantly reducing production time and cost by 'printing' tools, engine parts or even entire spacecraft," said Michael Gazarik, Nasa's associate administrator for space technology.
SLM is not the only unusual manufacturing technique being explored by Nasa.
The agency has also asked researchers at Washington State University to see whether it would be possible to 3D-print objects out of powder made from lunar rocks.