Researchers used the high-energy laser (HEL) to disable a boat by setting fire to its engines off the coast of California.
Similar systems had previously been tested on land, however moist sea air presented an extra challenge as it reduces a beam's power.
The navy said that ship-borne lasers could eventually be used to protect vessels from small attack boats.
The US military has been experimenting with laser weapons since the 1970s.
Early systems used large, chemical-based lasers which tended to produce dangerous waste gases.
More recently, scientists have developed solid state lasers that combine large numbers of compact beam generators, similar to LEDs.HELs fire The US Navy system uses a Joint High Power Solid State Laser mounted on deck
Until now, much of the development of HELs has focused on shooting down missiles or hitting land-based targets.
The latest round of tests showed its wider possibilities, according to Peter Morrison from the Office of Naval Research.
"This test provides an important data point as we move toward putting directed energy on warships.
"There is still much work to do to make sure it's done safely and efficiently," he said.
While a weaponised system would likely be restricted to military vessels, merchant shipping has also expressed an interest in laser technology.
A gun which uses visible laser light to temporarily blind pirates was announced by BAE Systems in 2010.
The technology is still being tested, ahead of a commercial launch.
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