NASA on Saturday said the hypersonic aircraft flew at seven times the speed of sound after being dropped from the wing of a modified B-52 bomber, boosted by an auxiliary rocket to an altitude of nearly 100,000ft.
The aircraft, a cross between a jet and a rocket, flew on its own for 10 seconds before plunging into the Pacific Ocean.
"This is a success. Everything worked as planned," said NASA spokeswoman Leslie William.
"So far everything has been successful," she added.
NASA says the prototype engine was destined to eventually power a new generation of space shuttles.
The test of the tiny prototype, only 3.6m in length, marked the first time a non-rocket, air-breathing jet engine has powered a vehicle in flight at hypersonic speeds, defined as speeds above Mach 5.
The previous world speed record was established by an SR-71 Blackbird spy plane, which flew at Mach 3.2.
An experimental X-15 plane was able to fly at Mach 6.7, but with a rocket engine.