"The ultra-precision anti-ship rocket blasted off from a rocket boat. The intelligent rocket precisely sought, tracked and hit the 'enemy' ship after flying there safely," KCNA reported on Saturday.
The agency added that the new rocket would be deployed throughout North Korea's navy "before long."
The missile was fired from a small naval vessel from North Korea's East Sea Fleet; the country's leader Kim Jong-un is reportedly keeping a watchful eye on the test.
The missile has been touted by state media as a "new type of cutting-edge anti-ship rocket" that should "bring a great change to the navy's defense of territorial waters."
Reuters quoted Jeffrey Lewis of the California-based Monterey Institute of International Studies as saying that the new missile seems to be identical in design to the KH-35, a Russian-made high-speed anti-ship missile which is capable of flying just meters above the sea.
The test comes in the run-up to the US-South Korean military drills, which are scheduled to take place this spring on the Korean Peninsula.
Washington and Seoul have repeatedly blamed Pyongyang for developing rocket capabilities that they say are required for the creation of an effective inter-continental ballistic missile.